Posts about: "TCAS (All)" [Posts: 152 Page: 2 of 8]

NIBEX2A
January 31, 2025, 14:47:00 GMT
permalink
Post: 11818263
Interestingly, if the SMS works in the US the same as everywhere else in the world, procedures should be audited on a regular basis, with a focus on any changes which may have invalidated the original assumptions made about the frequency of hazards and associated risks. These procedure reviews would also take place after receipt of any safety reports where the procedure could have been a contributing factor.

The NASA ASRS database contains safety reports raised over the US. A quick search with the term “helicopter” produced 40+ reports with the highlights shown below.. (apologies, to save time these are all copy and pasted) There are more, but I appreciate that most of us have annual eye examinations to pass so didn’t want to overdo it!

1. While we were flying the river visual to Runway 19 into DCA we received a TCAS alert. We were around SETOC or just past it and fully configured to land. There was, what I could only guess as I never saw it, a helicopter about 300ft below us. The TCAS showed it climbing but at a very very slow rate as it never showed closer than 300ft to us. When we flew over top of it, we got a “monitor vertical speed alert from TCAS which we then pitched into the green arc on the VSI which was -300fpm or greater. After we received the “clear of conflict” the FO corrected and got back on glide path. I assessed that we were still within stable approach criteria and we continued the approach and landed in DCA without further issue. We never received a warning of the traffic from ATC so we were unaware it was there. Suggestion: Need to have better separation for DCA traffic on the river visual to the helicopter traffic that is flying up and down the river. Maybe by timing the separation of when we began the approach to where that traffic will be when we cross overhead.

2.
ATC delayed switch from Approach to Tower led to TA and resulting altitude deviation causing a GPWS Caution. Tower then issued a low altitude alert. Helicopter traffic was heading up the Potomac while we were on the river visual approach did not alert us to the on coming traffic. By the time Tower responded we had a RA to descend which led to a GPWS and low altitude alert from Tower. We confirmed traffic in sight and maneuvered back on coarse to correct the deviation, in judgement the safety of flight was not compromised as such we continued the approach to landing on Runway 19. As I believe a go-around would have exacerbated the situation and led to further problems.

3.
I was working the Local and Helicopter positions combined at DCA ATC. I have been CPC/FPL for [a short time].

I accepted a handoff from Potomac TRACON on Aircraft X 2 miles west of ZZZ. Aircraft X contacted DCA Tower and requested to fly Route 1-Route 4 -ZZZ1 and then to ZZZ2. I radar contacted Aircraft X, approved the request and issued the altimeter.

Aircraft Y called on a seven mile final to DCA and requested to land on Runway XX. I then I cleared Aircraft Y to land.

Note. My standard practice for helicopter s flying the DCA helicopter route is to issue any pertinent landing traffic by the time the helicopter s pass over the South Capitol Street Bridge.

Aircraft X asked if I had issued traffic on the aircraft landing Runway XX. I thought I had applied my standard practice of issuing traffic to the helicopter s over the bridge so I informed Aircraft X that I had issued the traffic.

Once Aircraft Y landed, he asked about the flight of three helicopter s off his right. I informed him I had issued traffic to Aircraft X.

Neither aircraft declared a near miss on frequency. At all times I had maintained Tower applied visual separation between Aircraft X and Aircraft Y.

I recommend recurrent helicopter training for the facility to prevent this incident from occurring in the future with other controllers.

4


Our flight] into DCA was in a NMAC. We were supposed to circle from the visual Runway 1 to instead land on 33. We followed the [company] station bulletin procedures exactly as planned and came within very close contact of another aircraft. This occurred about 400 feet off the ground to the point where the pilot monitoring had to take the controls to make a correction in order to prevent it from becoming a midair collision. After there was action taken to make a correction from the close call, we were then informed by DCA tower of close traffic although at that point it would have been too late. I have flown with people who for the purpose of having a better chance of a stabilized approach would have had a wider circle to land procedure which I'm sure would have almost definitely ended in the collision of two aircraft over the turn to final for 33 in DCA. There was an extreme lack of communication between DCA Tower to [our flight] or DCA Tower to the associated helicopter who did not ever pop up on TCAS which I'm assuming is due to a lack of an operating transponder. No TCAS RA was associated with this event.

This occurred due to an extreme lack of communication between DCA Tower and [our flight] or DCA Tower and the associated helicopter . Otherwise the other reason this may have happened is because of an unclear idea of where aircraft should be located during Runway 33 circle to land operations. I believe I was on track with what the [company] guidelines are for that particular procedure but there is a possibility that the other traffic operating around that area may not be aware of where exactly we are located or maybe they don't have a specific guideline to keep the arriving traffic separated from the low flying helicopter s.

5

I understand DCA is a busy airport, I was based there for years. The military low level helicopter traffic that routinely is in the DCA traffic area complicates matters. But this is probably the most dangerous airport in the United States, strictly based on the the fact the controllers are pushing, pushing, pushing, in an attempt to handle the traffic they have.

6


We were cleared to circle to and land on runway 33. ATC also added that there was a low level helicopter and that the helicopter had us in
sight. At the Wilson bridge we turned to the northeast to set ourselves up for a landing on runway 33. We continued normally and started our turn to final.

when I saw an opposite direction helicopter very close to our altitude, but slightly below us and climbing. I was about to initiate the go around
regardless of the TCAS when we got the RA. As we started the go around I saw the helicopter make an aggressive descent. We were given a
turn to the east and a climb to 2,000 feet which we complied with. After that, we cleaned up the plane, setup for another approach, and landed
on runway 1 without incident. Once we cleared the runway, ground control asked me if I wanted to call the DCA tower supervisor for an
explanation of what happened. I gladly accepted. The tower supervisor I spoke with told me a few things that explained what may have
happened. Number one, he said that the helicopter s operating in that area should NEVER be above 200 feet. According to him, the helicopter
was at 800 feet, clearly not where he was supposed to be. He also explained that ATC may have taken their eyes off the helicopter for a
second because they would never expect those helicopter s to do something that egregious. That seems plausible given the fact that I've
never seen a helicopter in that area at that altitude. He suggested that it was most probably a deviation on the part of the Pilot of the
helicopter , and a loss of aircraft separation that was also the fault of the helicopter pilot.

Helicopter pilots in and around DCA should adhere to ATC instructions.

7


It was the end of a long day and the events were happening very quickly during a high workload portion of the flight. As all pilots know, the River Visual is a very demanding approach during the best of circumstances. It is very labor intensive when done at night during periods of high traffic volume. The advertised approach in use at DCA was the LDA 19 with VASI being out of service. During the initial approach, Potomac asked if we would accept the charted River Visual approach (VASI back working) and we did. At approximately the 7 DME point we were in the end process of configuring the airplane for landing and the First Officer was accomplishing the Landing Checklist. The radio chatter was considerable and the Tower at some point advised us of helicopter traffic ahead and to the left (I believe he said 10 to 11 o'clock) and he was going to pass from left to right, below us and he "HAS US IN SIGHT." It has to be noted that these traffic calls and helicopter s have unfortunately become background noise. There are always numerous military and government helicopter s running up and down that river at all times of the day and night. Because of this, what would normally be alarming at any other airport in the country has become commonplace at DCA. The FAA allows these aircraft to operate in this environment and we have no choice, but to accept it and deal with it. Therefore, the helicopter s being very close are not out of the norm. As you can imagine, I was concentrating on the approach and doing the required gyrations to stay over the river and not violate the White House prohibited airspace, and to keep the aircraft on the proper vertical profile. The Runway 19 visual was loaded in the FMGC and I was using it as a backup to my eyes. I was 'dead on' the donut and everything looked normal. I was at or very slightly above the recommended altitudes at each DME point. As I was approaching 4 DME, I caught a glimpse of the helicopter out of my left window and he did look higher than I expected to see him. I asked the First Officer to confirm if he was going to cross from north to south. He confirmed, however I directed him to ask the Tower and confirm it with them because it did not look right. The First Officer could not get a word in with the Tower. It was at that point, we got a TCAS "TRAFFIC" call. Again, this is not out of the 'norm' for DCA. I was getting ready to take possible evasive action because it was getting uncomfortable; all this while trying to fly the demanding profile. Within seconds, we got a TCAS alert, "MONITOR VERTICAL SPEED." I complied with the TCAS alert and was thinking of going around but it all happened so very quickly that the point was moot. The helicopter passed 200 FT (MAX) below us. We were at 900 FT, slightly above the path. The Tower never called out the traffic beyond the first notification. The landing was uneventful. Due to the workload, we asked the Ground Controller for the Tower number and I called when I got to my vehicle. I called the Tower and spoke with the Controller in charge. At first it was it was obvious he was somewhat on the defensive and I had to press the point and ask very specific questions about the standard helicopter operations in the area. After some prodding, he admitted that it was a military helicopter flying from/to Ft. Meade and that he was at 700 FT and was "a little higher than normal." I asked what altitude was he supposed to be at and he replied, "three to four hundred feet." In addition, he did admit that the Tower version of collision avoidance did go to alarm but before they had a chance to react, the event was over. I cannot imagine what business is so pressing that these helicopter s are allowed to cross the path of airliners carrying hundreds of people! I do not understand why they are not crossed IN-BETWEEN arrivals. They have at least 4 miles between these arriving aircraft and it seems that would be more prudent.

8


We were on the Mount Vernon Visual Approach to Washington National Airport, and the Tower instructed us to circle to land on Runway 33. While we made our approach to Runway 33, Tower advised a helicopter was maneuvering at our 12 o'clock position. As we continued our approach, Tower instructed the helicopter to "make a right 360 for a jet on a 2 mile final for Runway 33, and to report him in sight" (referring to our aircraft.)

The Tower then asked the helicopter if he had us in sight. He replied "yes", and the Tower told him to maintain visual separation. As we began our turn from base to final, the helicopter made what looked like a right turn directly into our flight path. The Captain, the pilot flying, made a hard right turn and executed a missed approach to avoid a collision. I'm not sure how close we came to the helicopter since it was on the left side of the aircraft, but I would guess it was only a few hundred feet.

9

WE WERE EXECUTING AN ILS IN IMC. AS MY FO ANNOUNCED 'APCHING MINIMUMS, RWY IN SIGHT,' I BEGAN MY TRANSITION FROM FLT DIRECTOR REF TO VISUAL REF FOR A HAND FLOWN LNDG. MY AIRSPD WAS PROBABLY AROUND 130-135 KIAS. AS I WAS TRANSITIONING I SUDDENLY SAW A DARK COLORED MIL HELI ON MY APCH PATH. HE BLENDED IN VISUALLY WITH THE DISMAL WX CONDITIONS. I DID NOT NOTICE ANY ACFT LIGHTING. AS I SAW HIM, SO DID THE DCA TWR CTLR. THE CTLR ISSUED AN IMMEDIATE AND FORCEFUL ATC INSTRUCTION TO THE HELI. THE HELI EXECUTED AN ABRUPT EVASIVE MANEUVER AND DISAPPEARED INTO THE FOG. I LANDED SAFELY. THIS ENTIRE EVENT LASTED ABOUT 3-4 SECONDS. MY ACFT (BOEING 757) CONFIGN WAS GEAR DOWN, FULL 30 DEG FLAPS, ON SPD, ON COURSE, ON GLIDE PATH. EVASIVE MANEUVERING CAPABILITY IS LIMITED UNDER THESE CIRCUMSTANCES. MY ALT WAS ABOUT 300-400 FT ABOVE THE POTOMAC RIVER. ARPT TERMINALS AND CTL TWR WERE TO MY L, PROHIBITED AREA P-56 WAS TO MY R, AND THE HELI IN QUESTION WAS IN THE WX IN FRONT OF ME SOMEWHERE. I DIDN'T FEEL I COULD EXECUTE A MISSED APCH WITH THAT ACFT IN THE FOG IN FRONT OF ME. WE WERE STILL ON LNDG PROFILE AND I DECIDED LNDG WAS THE SAFEST COURSE AVAILABLE. WE MADE A NORMAL EXIT FROM THE RWY TO THE L WITH MUCH LNDG ROOM LEFT ON RWY 36. TAXIED TO THE GATE AND PARKED. MADE AN IMMEDIATE PHONE CALL TO THE TWR SUPVR AND RPTED THE INCIDENT. THEN CALLED MY AIRLINE FLT MGMNT SUPVRS AND RPTED THE INCIDENT AND MADE A WRITTEN RPT TO THE AIRLINE SAFETY DEPT UPON ARR AT MY BASE THAT NIGHT. I AM GLAD THE VISIBILITY WAS GOOD ENOUGH FOR THE CTLR TO SEE THE HELI IN TIME TO TAKE ACTION. IF THE VISIBILITY HAD BEEN ANY LESS HE WOULDN'T HAVE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THAT DURING HIS SPEAKING WITH THE TWR FACILITY AT DCA, A CTLR IN TRAINING WAS HANDLING THE MIL TFC AT THE N END OF THE ARPT UNDER THE JURISDICTION OF ANOTHER, MORE EXPERIENCED, CTLR. THE SECOND CTLR IS THE ONE THAT TOOK OVER THE MIKE AND ORDERED THE HELI TO LEAVE THE APCH ENVIRONMENT OF THE LNDG TFC. THE RPTR STATES THAT HIS TRAINING WOULD NORMALLY CAUSE HIM TO EXECUTE A MISSED APCH BUT THAT THE POSSIBILITY OF ANOTHER ENCOUNTER WITH THE SAME ACFT SEEMED LIKE A GOOD POSSIBILITY AND SO DECIDED THAT LNDG WAS THE SAFEST PATH TO FOLLOW. HE SAID THAT THE PHONE CONVERSATION REVEALED THAT EXTENSIVE TRAINING FOR A MIL EXERCISE OR OP WAS IN PROGRESS AND WAS BEING STAGED FROM THE N PART OF THE DCA COMPLEX. THE RPTR DOESN'T KNOW WHETHER THE HELI PLT MISUNDERSTOOD HIS INSTRUCTIONS OR WHETHER THE CTLR ISSUED SUCH INSTRUCTIONS IN THE FIRST PLACE.

10
WE WERE ON THE RIVER VISUAL APCH TO RWY 18 AT DCA. THERE WAS A MIL HELI OPERATING A TRAINING FLT FLYING N TO S OVER THE RIVER AT 500 FT MSL. WE APPEARED TO BE AT LEAST 80 KTS FASTER (WHILE IN OUR LNDG CONFIGN) THAN THE HELI. TWR ADVISED US OF THE HELI AND THAT HE HAD US IN SIGHT AND HE WOULD MAINTAIN VISUAL SEPARATION WITH US. WE OVERTOOK ALMOST DIRECTLY ABOVE THE HELI AT ABOUT 3.5 DME AND 1100 FT MSL, RIGHT AT THE TURN IN THE RIVER THAT IS REQUIRED ON THE APCH. WE RECEIVED AN RA FROM OUR TCASII AT 1100 FT. WE FLEW AS FAR TO THE E SIDE OF THE RIVER AS WE COULD TO MAINTAIN VISUAL ON THE HELI ON THE W SIDE OF THE RIVER. WINDS WERE OUT OF THE SW AT 15-20 KTS. THE TCASII INDICATED CLR OF CONFLICT. WE STARTED TO DSND AGAIN AND AT 900 FT AGL, RECEIVED ANOTHER RA FROM OUR TCASII. AT THAT POINT IN THE APCH, THE RIVER TURNED BACK TO THE SSW. AS WE MADE OUR R TURN WE REGAINED VISUAL WITH THE HELI AND CONTINUED TO DSND. TCASII GAVE US 'CLR OF CONFLICT' AND WE FINISHED THE APCH AND LANDED. AFTER LNDG, I CALLED THE TWR SUPVR AND HE LISTENED AND SAID THIS WAS NORMAL. I HAVE FLOWN THIS APCH AT LEAST 15 TIMES AND I AM VERY FAMILIAR WITH THIS APCH. HOWEVER, I CONSIDERED THIS APCH PUSHING THE ENVELOPE FOR SAFETY, WITH THE AMOUNT OF ATTN I HAD TO GIVE TO THE HELI WHILE FOLLOWING THE RIVER AND DSNDING IN A XWIND AND AT A HIGH LNDG WT. THE TWR NEVER MADE IT CLR TO US WHERE THE HELI WAS GOING. ON THE PHONE THE SUPVR SAID THEY TRAIN FLYING N TO S AND BACK AT 500 FT. APPARENTLY, THEY DO THIS FROM 2 DME N TO 10 DME, BASICALLY UNDER THE WHOLE APCH. WHY CAN'T THEY DO THIS AFTER 10 O'CLOCK PM OR DURING LOW TFC FLOW PERIODS? AT THE VERY LEAST, THE ACFT SHOULD BE SPACED BETTER SO AS NOT TO FLY SO CLOSE TO THE HELI WHILE ON THE APCH. I HAVE ENCOUNTERED HELIS PREVIOUSLY WHILE SHOOTING THIS APCH, HOWEVER, THEY WERE ALWAYS CLOSER IN SPD TO US AND THEREFORE WE WOULD NOT OVERTAKE THEM AS FAST, OR WE WERE SPACED BETTER. ALSO, THEY ALWAYS HAD A DEST THAT WE WERE ADVISED OF. I'M SENDING IN THIS RPT BECAUSE I WAS NOT COMFORTABLE WITH THE LEVEL OF SAFETY INVOLVED WITH FLYING WITHIN 400 FT VERTLY OF A HELI AND THAT IS CONSIDERED A NORMAL OP.
11
DURING ILS APCH, SBOUND, HELI COMING DOWN POTOMAC RIVER ABOUT 500 FT MSL, TFC CALLED BY TWR, WE DIDN'T SEE IT. WE GOT AN RA ON TCASII -- HAD TO FOLLOW RA INSTRUCTIONS. THEN WE WERE HIGH ABOVE GS, HAD TO DSND MORE RAPIDLY THAN WE WANTED TO IN ORDER TO LAND. THIS HELI CONFLICT AROUND DCA IS A DAILY PROB! GOING TO TA ONLY ON TCASII WOULD DEFEAT PURPOSE OF TCASII. LNDG ACFT SHOULD NOT HAVE TO ACCOMMODATE HELI'S. THIS IS AN ACCIDENT WAITING TO HAPPEN.

12

I WAS TURNING FINAL FOR STOL LNDG RWY 21 DCA. I SAW A HELI APCHING ON CONFLICTING FLT PATH. IT WAS APPROX 400 FT BELOW US, BUT WE WERE DSNDING FOR LNDG. I ADVISED DCA TWR OF TFC. HE SAID 'TFC LOW LEVEL, 200 FT.' JUST AS I WAS GOING TO MANEUVER TO AVOID, THE CHOPPER MADE A STEEP TURN AWAY FROM US. AT THIS POINT WE WERE WITHIN 100 FT VERTICALLY AND 1000 FT HORIZLY. BECAUSE OF THE LIMITATIONS ON PERFORMING A STOL LNDG AT DCA, MY TURN TO AVOID HIM WOULD ALSO CAUSE A GAR. TWR HAD PUT US ON RWY 21 WHILE THE ARPT WAS IN A 'N' OP (ALL OTHER TFC LNDG ON RWY 36). I RECEIVED NO WARNING FROM TWR OF HELI TFC AND I HAD NO WAY OF KNOWING IF CHOPPER PLT HAD US IN SIGHT (UNTIL HE MADE THE EVASIVE TURN). THIS IS BY NO MEANS THE FIRST TIME OF SUCH AN OCCURRENCE AT DCA. I HAVE HAD MANY CONFLICTS WITH CHOPPERS, BOTH ON LNDG AND TKOF AT DCA. I HAVE TALKED TO TWR SEVERAL TIMES (INCLUDING THIS TIME) AND HAVE RECEIVED APOLOGIES AND ADMITTING OF ERRORS BUT THE PROB CONTINUES. THE HELI IS A VERY MANEUVERABLE ACFT. IF THE CHOPPER PLTS WOULD JUST GIVE US MORE SEPARATION, THE PROB WOULD BE SOLVED. WHEN THEY SEE US THEY COULD SLOW OR HOVER, TURN, ETC. CONFLICTS OCCUR WHEN TWR FORGETS TO ADVISE ME THAT CHOPPER HAS ME IN SIGHT AND THE CHOPPER MAINTAINS HIS 'TRAJECTORY' WHICH CONFLICTS WITH MY LIMITED ARR OR DEP AIRSPACE.

13

DURING RIVER VISUAL APCH DCA (LNDG RWY 18), 3 HELIS CROSSED OUR FLT PATH. THE FIRST CAUSED AN RA ON TCASII WITH A 0-300 FT CLB (WHICH WE FOLLOWED). THE HELI WENT DIRECTLY UNDER OUR ACFT WITH LESS THAN 300 FT SEPARATION. THE NEXT 2 HELIS CAUSED MONITOR VERT DSCNT ON THE TCASII. ALL 3 HELIS WERE ENCOUNTERED IN A DISTANCE OF LESS THAN 1 MI. THE TWR NEVER CALLED ANY TFC, UNTIL WE CALLED THE FIRST HELI IN SIGHT. THEN HE SAID 3 HELIS WERE XING THE RIVER. WITHOUT THE RA WE WOULD HAVE COME EVEN CLOSER THAN 300 FT TO THE FIRST HELI.

14

WASHINGTON APCH CTL CLRED ACR X FOR THE MT. VERNON 36 APCH. AT THE WILSON BRIDGE THE TWR CLRED US TO LAND STOL ON RWY 33. I TURNED OFF THE MT. VERNON 36 APCH ONTO A L BASE LEG FOR RWY 33. THE PATTERN FLOWN WAS SQUARE. I TURNED FINAL ABOUT 1/2 MI S OF THE E BANK OF THE POTOMAC RIVER. AT NO TIME WERE WE ADVISED OF A HELI IN OUR AREA AND WE DID NOT HEAR THE TWR TALKING TO A HELI ON 119.1 (1-WAY OR 2-WAY COM). WE DID NOT SEE A HELI DURING OUR APCH. THE SKY WAS HAZY AND THE SUN WAS OFF THE L SIDE. IT WAS DAYLIGHT. LINED UP ON FINAL AND STABILIZED FOR A STOL LNDG, I SUDDENLY CAUGHT SIGHT OF A PRESIDENTIAL TYPE HELI XING OUR FLT PATH, APPROX 50-100 FT BELOW AND 100 FT IN FRONT OF US AT OUR 11:30 POS, AS WE PASSED THROUGH 600 FT MSL. THE HELI WAS MOVING L TO R AT A GOOD SPD, BUT I DETERMINED A COLLISION WAS POSSIBLE AND IMMEDIATELY APPLIED PWR, PULLED UP AND CALLED 'GAR' TO THE FO. AS WE PULLED UP I CALLED OUT THE HELI TO THE FO WHO THEN SAW IT CLOSE AND BELOW AS IT PASSED OFF THE R SIDE. THE GAR WAS UNEVENTFUL AND COMPLIED WITH TWR INSTRUCTIONS WHICH WERE GIVEN AFTER WE CALLED WITH GAR AND NEAR MISS. THE TWR'S RESPONSE WAS 'ROGER AND UNDERSTAND' ONLY. THE HELI IN QUESTION DID NOT APPEAR TO ALTER COURSE OR FLT PATH UNTIL DSNDING AND LNDG AT ANACOSTRA. ON THE GND I ATTEMPTED TO CALL THE TWR ON LANDLINE BUT KEPT GETTING A BUSY SIGNAL (3 ATTEMPTS). SINCE I WAS DUE BACK OUT IN 10 MINS FOR MY NEXT FLT, I RETURNED TO MY ACFT AND CONTINUED ON MY SCHEDULE. I WAS NEVER ABLE TO DETERMINE IF THE TWR KNEW OF OR HAD TALKED TO THE HELI IN QUESTION. MANY TIMES THE TWR TALKS TO HELIS ON A DIFFERENT FREQ, BUT YOU CAN HEAR THE TWR'S COM TO THEM ON 119.1. THEY WILL USUALLY POINT OUT HELI TFC TO US AND COMMENT THAT THE HELI IS AT SUCH AND SUCH AN ALT, DIRECTION AND THAT THEY (THE HELI) HAVE US IN SIGHT. THIS INCIDENT WAS 'VERY' CLOSE AND FAR FROM THE NORM I'VE EXPERIENCED IN 15 YRS OF FLYING INTO AND OUT OF DCA.

15
HOT, HAZY AFTERNOON IN WASHINGTON (HAZE DID RESTRICT VISIBILITY) FLYING THE RIVER VISUAL APCH TO RWY 18 AT DCA, CREW IS DCA BASED SO WE ARE VERY FAMILIAR WITH THIS APCH. AT ABOUT 4-5 DME, TWR ASKED US IF WE COULD LAND ON RWY 15, I DECLINED AND SAID THAT I'D LIKE TO CONTINUE FOR RWY 18. TWR THEN ADVISED US THERE WOULD BE 2 HELIS COMING OUT OF THE TIDAL BASIN AREA. (IT IS NOT AT ALL UNCOMMON TO SEE HELIS XING OUR FLT PATH WHEN WE ARE TAKING OFF TO THE N AND CLBING). I COULD SEE A CONTACT ON OUR TCASII SCREEN -- JUST ONE TARGET -- AND BTWN 600 AND 500 FT ON FINAL, WE GOT AN RA THAT COMMANDED CLB. I HAD THE FO LEVEL OFF AT 500 FT, THE TARGET SHOWED 200 FT BELOW ON THE TCASII AND VERY CLOSE ABEAM ME (ON 5 NM SCALE) AND I NEVER DID SEE EITHER HELI. WE STARTED BACK DOWN WHEN THE TCASII SHOWED WE WERE PASSED THEM, WE WERE HIGH AS WE ROLLED WINGS LEVEL ON FINAL BUT, WE WERE STILL ABLE TO SAFELY COMPLETE THE APCH. I HAVE BEEN FLYING THIS APCH AT DCA FOR 7 1/2 YRS, AND THIS ONE REALLY GOT MY ATTN. TWR IS NOT CTLING THE HELIS, I CAN'T BE SURE THE HELIS HAVE ME IN SIGHT, I KNOW THE SECOND HELI IS LOOKING AT HIS LEAD -- THEREFORE, I KNOW HE IS NOT LOOKING AT ME, AND I AM DSNDING INTO HIM WHILE ON FINAL ON A CHALLENGING APCH. THIS HAD THE POTENTIAL TO BE A MIDAIR, AND UNFORTUNATELY, PROBABLY IS CONSIDERED ROUTINE OPS BY DCA TWR.

16
MANEUVERING IN GOOD VMC FOR LNDG ON RWY 21 AT DCA (CLRED FOR VIS APCH, MONITORING TWR FREQ FOR LNDG CLRNC). TWR ADVISED OF HELI TFC BELOW AND AHEAD. THIS TFC WAS SPOTTED FLYING SW WHERE ANACOSTIA RIVER MEETS POTOMAC. NO CONFLICT, INITIALLY. THE HELI, A MIL TYPE, THEN TURNED NW UP THE POTOMAC RIVER. THIS NOW BECAME AN IMMEDIATELY INCREASING TFC CONFLICT. CONVERGING FLT PATHS. I ASKED TWR TO PROVIDE SEP, HOPING HE WOULD STOP, SLOW OR TURN THE HELI. HE RESPONDED WITH, "MAINTAIN VIS SEP." MANEUVERING IN CLOSE FOR A STOL LNDG ALLOWS FOR VERY LITTLE LEEWAY FROM THE DESIRED FLT PATH. A GAR FROM THIS POS IS ALSO DANGEROUS. THERE WAS NO TIME TO COMMUNICATE THIS TO TWR AND THE HELI WAS ON A DIFFERENT FREQ. I CONTINUED AND LANDED VERY CAUTIOUSLY WHEN I REALIZED WE WOULD MISS TFC. HOWEVER, WE ONLY MISSED BY APPROX 300'. I FEEL THAT ATC (TWR) IGNORED ITS BASIC OBLIGATION OF PROVIDING SEP. THE HELI COULD HAVE EASILY BEEN SLOWED, STOPPED OR TURNED AS A MEANS OF AVOIDING AN IMPENDING COLLISION. TWR CERTAINLY WOULD HAVE BEEN AWARE OF BOTH ACFT'S FLT PATHS. I HOPE THEY (TWR) DO NOT THINK 200-300' IS A SAFE AMOUNT OF TFC SEP. THIS HELI CONFLICT, AND POOR ATC SEP OF IT, AT DCA IS AN ONGOING PROB. HERE IS AN ACCIDENT WAITING TO HAPPEN.



Subjects ATC  Circle to Land (Deviate to RWY 33)  Close Calls  DCA  FAA  Frequency 119.1  Radar  Separation (ALL)  TCAS (All)  TCAS RA  Traffic in Sight  Visual Separation

Links are to this post in the relevant subject page so that this post can be seen in context.

7 recorded likes for this post.

Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

island_airphoto
January 31, 2025, 15:55:00 GMT
permalink
Post: 11818313
Originally Posted by TCAS FAN
Which could indicate that the controller was simultaneously transmitting on two frequencies (VHF+UHF) and the frequencies were not cross-coupled, resulting in the traffic on VHF not being able to hear the traffic on UHF, and vice-versa.

Cross-coupling, whereby aircraft transmissions are re-broadcast on the other frequency being used is a mandatory requirement at civil ATC units in UK. This being done to facilitate situational awareness of other traffic by all crews.

That would defeat the original intent of the separate helo controller herding them around without having to deal with the very busy airplane tower frequency. Obviously this totally fails when there is only one person

Subjects ATC  Situational Awareness  TCAS (All)

Links are to this post in the relevant subject page so that this post can be seen in context.

1 recorded likes for this post.

Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

moosepileit
January 31, 2025, 17:13:00 GMT
permalink
Post: 11818379
Originally Posted by fdr
Heathrow is great, calm and polite.
Even as they apologize for setting up a near miss, they are, polite and calm.
They are human, and subject to the same frailties as the rest of us.
They are sure polite though.

Heathrow suffers from the problem that their local airspace is.. logical, as are the flight paths, and generally the runway utilisation. They don't have the benefit of the special design skills applied to JFK's terminal procedures which seem to have been designed to give cardio workouts for the controller and the pilots. Masterful airspace design.

JFK, making Abuja look attractive.
Originally Posted by SASless
Re-stated I being the target being "seen" would be thinking "Is it for sure me he is seeing?" and I would be looking for him to make darn tooting I KNEW where the conflicting traffic was as ATC thought it to be a conflict.

I learned that from during my Student Pilot days and it was reaffirmed till I retired from flying.

The Rule is "see and be seen"....which I read as being a two way street kind of situation.

When there is doubt...there is no doubt....remedy the situation as quickly and safely as possible.

If your aircraft is so complex and difficult to fly, or your procedures do not require or allow you to look out when appropriate, and that one of you cannot be spared to take a look out the window now and then....or if you think there is no need for you get your scan outside because you think yourself too busy inside.....there is something close to home that warrants changing.

Bottom line....nothing prevents you from doing a "missed approach" and give it a second try if it eliminates a critical risk of some kind. Even Air Line Pilots do not have to land on every approach and need to kick the mindset every second counts and remind their management that an occasional delay's expense is far cheaper than an accident. It also might make the difference between being retired and enjoying life and just being another statistic or name on a list of those killed In a crash.

This discussion about who is burdened with the responsibility for traffic separation between ATC and Pilots omits one thing.....the PIC of each aircraft is equally responsible for the safety of their own aircraft. More importantly, ATC Controllers might have to live with their mistakes but Pilots die by theirs.
The world is not that black and white.
DCA, and others nornalize collision alerts in the background of a significant % of ATC transmssions.

TCAS RA heights show mandatory Day, VMC go arounds the day prior- but how close was the helicopter to the 737 not going around 2 minutes earlier the day prior, so low TCAS TA only height below 900' allows continuing?

You think the CRJ crew, below 500', rolling out of a left turn to 33 sees the helicopter to their right or even notices the TCAS TA display? Maybe it gets a glance IF the short final is wired. Problem is the Traffic aural is already expected in the airspace, same as hearing the ATC collision alarms in their transmission background.

There will be line of sight recreations in the reports. The CRJ will not have but a scant chance to have seen the PAT25, with caveats- the CVR has to be heard.

Pat25 likely had a 500 hour pic getting a checkride in the right, distant seat and the radio PM/1000 hour pilot in left seat, seeing only AAL3130 and trying to figure out how to pass behind, cognitive dissonance with what is seen..

3 seconds later, all ends.

James Reason, Diane Vaughan, NASA, et al...

Subjects ATC  CRJ  Close Calls  DCA  PAT25  Pass Behind  Pass Behind (All)  Separation (ALL)  TCAS (All)  TCAS RA

Links are to this post in the relevant subject page so that this post can be seen in context.

No recorded likes for this post (could be before pprune supported 'likes').

Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

vanHorck
January 31, 2025, 18:23:00 GMT
permalink
Post: 11818434
Now a lapsed PPL ME, whenever I needed to cross flight paths around airports, I believe I learned to cross overhead the field instead of crossing approach/departure paths. I always thought this was prudent. Asking to fly across approach/departure seems daft to me, it's just a few seconds extra and so much safer, even if the corridors change when runways change.. Now understanding that the modern TCAS is inoperable below 500 ft for understandable reasons, it makes even more sense.

Subjects TCAS (All)

Links are to this post in the relevant subject page so that this post can be seen in context.

1 recorded likes for this post.

Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

MissChief
January 31, 2025, 22:09:00 GMT
permalink
Post: 11818564
Thumbs down

Originally Posted by Bratchewurst
Many years ago, shortly after I got my instrument rating, I flew a friend from St. Paul to St. Louis in a rented C172. Of course I filed IFR, being anxious to get more practice in the system. We were maybe 10-20 miles SW of MSP in level flight when I heard the controller tell a Northwest flight of Cessna traffic somewhere in our direction; there was another Cessna in the area as well. NW called \x93traffic in sight.\x94 Maybe 10 seconds later my passenger pointed very excitedly behind us and to our left. There was a NW 727, maybe 200-300 yards behind us and climbing through our altitude from left to right. Very fast.

I\x92ve always wondered if they really saw us or the other Cessna. It was probably the closest I\x92ve ever been to another aircraft not in the pattern. It felt way too close.

\x93See and avoid\x94 is really not the basis for safe separation of traffic in the air. Depending on it at night in airspace as busy as DC is choosing poorly.

TCAS has mostly solved the separation problem for every phase of flight except very close to the airport or on the ground. If the industry is going to short-staff ATC and keep cramming more traffic into the same airspace, the industry needs to develop and equivalent solution for those phases of flight as well.
TCAS has definitely not mostly solved separation. Your example cites that, unless you were not IFR, in contrary to what you wrote. I experienced pop-up traffic at 5200 feet, north of Daytona, which passed 100-150 yards to our left at the same altitude. RA was extremely late for us. ATC had given no indication of conflicting traffic. Nor was it on frequency. I was operating an A330 with 325 pax and 12 crew. .

Subjects ATC  IFR  Separation (ALL)  TCAS (All)

Links are to this post in the relevant subject page so that this post can be seen in context.

No recorded likes for this post (could be before pprune supported 'likes').

Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

Bratchewurst
January 31, 2025, 22:30:00 GMT
permalink
Post: 11818579
Originally Posted by MissChief
TCAS has definitely not mostly solved separation. Your example cites that, unless you were not IFR, in contrary to what you wrote. I experienced pop-up traffic at 5200 feet, north of Daytona, which passed 100-150 yards to our left at the same altitude. RA was extremely late for us. ATC had given no indication of conflicting traffic. Nor was it on frequency. I was operating an A330 with 325 pax and 12 crew. .
My incident was long before TCAS. I was definitely IFR. I accept that my conclusion that TCAS has \x93solved separation\x94 in most cases is based on the absence of news reporting of such incidents - in marked contrast to the reporting of all the runway incursions and close calls in situations where TCAS is inhibited. Admittedly that\x92s more anecdote than data.

Subjects ATC  Close Calls  IFR  Separation (ALL)  TCAS (All)

Links are to this post in the relevant subject page so that this post can be seen in context.

1 recorded likes for this post.

Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

MarkD
February 01, 2025, 02:01:00 GMT
permalink
Post: 11818703
Vasaviation has posted a different PAT helicopter being involved in a TCAS RA and go-around for a different passenger aircraft the previous day. The video indicates it coming close to two others and there was a Tower controller change (at least to the extent that there is a different voice in the audio) just about the time the RA occurred


Subjects ATC  TCAS (All)  TCAS RA

Links are to this post in the relevant subject page so that this post can be seen in context.

1 recorded likes for this post.

Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

Denflnt
February 01, 2025, 03:09:00 GMT
permalink
Post: 11818724
I tend to think ATC and, likely, the FAA will be shown as primary at fault with this:

1. The CRJ was on approach to 1 and then was asked to divert to 33. They complied, which added to their workload. From what I understand, that runway is rarely used for commercial aircraft. So, ATC added to the CRJ's workload while introducing and "unusual event." The CRJ crew appears to have acted professionally in changing their approach.
2. ATC didn't hold the helo short of the runway path, instead relied on them to correctly identify an aircraft, at night, over an urban area. That introduced a "single point of failure" to an already complex situation.
3. There was no way for the helo to pass safely under the CRJ at the altitude of impact.
3. I don't recall hearing ATC asking the CRJ if they could see the helo, though they already overtasked them. At that point, I don't think they could do anything at that point to prevent the collision.

Other factors may come into play, such as if ATC was properly staffed that night. I've read that DCA had two incidents that week where an aircraft had to perform a "go around" because of helo traffic. Also, was the CRJ's TCAS system operational?

This was completely preventable if things work they way they're supposed to.


Subjects ATC  CRJ  DCA  FAA  TCAS (All)

Links are to this post in the relevant subject page so that this post can be seen in context.

No recorded likes for this post (could be before pprune supported 'likes').

Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

KRviator
February 01, 2025, 03:34:00 GMT
permalink
Post: 11818738
Originally Posted by Denflnt
I tend to think ATC and, likely, the FAA will be shown as primary at fault with this:

1. The CRJ was on approach to 1 and then was asked to divert to 33. They complied, which added to their workload. From what I understand, that runway is rarely used for commercial aircraft. So, ATC added to the CRJ's workload while introducing and "unusual event." The CRJ crew appears to have acted professionally in changing their approach.
2. ATC didn't hold the helo short of the runway path, instead relied on them to correctly identify an aircraft, at night, over an urban area. That introduced a "single point of failure" to an already complex situation.
3. There was no way for the helo to pass safely under the CRJ at the altitude of impact.
3. I don't recall hearing ATC asking the CRJ if they could see the helo, though they already overtasked them. At that point, I don't think they could do anything at that point to prevent the collision.

Other factors may come into play, such as if ATC was properly staffed that night. I've read that DCA had two incidents that week where an aircraft had to perform a "go around" because of helo traffic. Also, was the CRJ's TCAS system operational?








This was completely preventable if things work they way they're supposed to.
You mean, like an aircraft (who themselves requested visual separation) assigned responsibility for separating itself from another, to actually seperate itself from the other and not fly into it?!?

Everything else is moot, really...

Subjects ATC  CRJ  DCA  FAA  Separation (ALL)  TCAS (All)  Visual Separation

Links are to this post in the relevant subject page so that this post can be seen in context.

No recorded likes for this post (could be before pprune supported 'likes').

Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

YRP
February 01, 2025, 14:45:00 GMT
permalink
Post: 11819065
Originally Posted by TCAS FAN
Which could indicate that the controller was simultaneously transmitting on two frequencies (VHF+UHF) and the frequencies were not cross-coupled, resulting in the traffic on VHF not being able to hear the traffic on UHF, and vice-versa.

Cross-coupling, whereby aircraft transmissions are re-broadcast on the other frequency being used is a mandatory requirement at civil ATC units in UK. This being done to facilitate situational awareness of other traffic by all crews.
I was going to ask if cross-coupling is done in the US.

It\x92s pretty common in Canada, both at Tower and enroute IFR sectors.

It\x92s not just for situational awareness, also to prevent overlapping transmissions from aircraft on the two frequencies. So you don\x92t have to try to listen to both as the controller.

Even without that the controllers here almost always transmit on all their frequencies rather than just the one the aircraft is on.

Subjects ATC  IFR  Situational Awareness  TCAS (All)

Links are to this post in the relevant subject page so that this post can be seen in context.

1 recorded likes for this post.

Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

Lascaille
February 01, 2025, 14:46:00 GMT
permalink
Post: 11819066
Originally Posted by YRP
But the airspace & procedure seems to not tolerate mistakes. There ought to be some safety margin. While not the primary fault, it could be improved.
Surprised you say that; to me the airspace design and procedures are absolutely the primary fault. TCAS was literally invented because intersections with crossing traffic occur at cruise level even though airway separation / quadrantal rule should keep you out of each other's way.

This airspace literally has an intersection with crossing traffic designed into it. You can't hit something you're not close to.


Subjects Separation (ALL)  TCAS (All)

Links are to this post in the relevant subject page so that this post can be seen in context.

3 recorded likes for this post.

Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

Northern Monkey
February 01, 2025, 15:04:00 GMT
permalink
Post: 11819085
Speaking as someone who has been flying heavy metal into and out of the states for years, I find this accident obviously tragic but entirely unsurprising. I have had multiple instances of close calls with helicopters at various US airfields over the years down to completely inappropriate visual clearances being issued to the helicopter traffic - including clearances to fly under the active approach. On occasion helicopters appear to have taken it as almost a challenge to get as close as possible.. almost waving distance on one occasion at SJC. Apart from the risk of collision this is incredibly distracting for the crew of the other aircraft whose primary job at that point should be the monitoring of the flight path. Couple this with the practice of operating TCAS in TA only (as appears to be permissible in some instances for local US carriers) or indeed RAs being inhibited due to the low altitudes involved, and you have a recipe for disaster. Especially at night. And that is before we get on to the, all too often, casual level of R/T employed in the US.

Hopefully this event will spur a wider review of such practices rather than narrowly focusing on heli-lanes in the vicinity of Reagan.

Subjects Close Calls  TCAS (All)  TCAS RA

Links are to this post in the relevant subject page so that this post can be seen in context.

5 recorded likes for this post.

Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

moosepileit
February 01, 2025, 15:17:00 GMT
permalink
Post: 11819090
Originally Posted by Luc Lion
200 ft is not the separation between the 2 aircrafts, it's the maximum altitude allowed in the helicopter corridor. As the airplane on approach is supposed to be at about 250 ft when crossing this corridor, there is no way a 200 ft separation could ever have been achieved.
500' vertical, parallel separation is what a TCAS RA/Resolution provides. At the heights of the involved, RAs are suppressed. Hence why the Republic had to go around the day prior, but the 737, earlier and lower did not.

500' is also the VFR and IFR vertical offset standard. If unable to achieve, should not be allowed. 200' leg must be to be 500' below south flow DCA departures, so North flow arrivals need a better gate.

Subjects DCA  IFR  Separation (ALL)  TCAS (All)  TCAS RA  VFR

Links are to this post in the relevant subject page so that this post can be seen in context.

No recorded likes for this post (could be before pprune supported 'likes').

Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

Chesty Morgan
February 01, 2025, 21:23:00 GMT
permalink
Post: 11819308
Originally Posted by RatherBeFlying
We have to wait for the NTSB to let us know what, if any, traffic appeared where on the CRJ panel, how prominent it appeared, or if there were aural warnings.

I have received warnings and an alarm for Flarm traffic. When I have seen ADS-B traffic I have been able to stay far enough away that I haven't been able to verify whether warnings and alarms are provided for ADS-B traffic if it becomes a threat.
Airline pilots do not, as a matter of course, avoid TCAS traffic unless given an RA, TCAS is notoriously inaccurate laterally, we will try to acquire traffic visually and may then react IF we can.

Also depending on the range selected on the TCAS or ND display you might get a load of garbled nonesense.

Subjects ADSB (All)  CRJ  NTSB  TCAS (All)

Links are to this post in the relevant subject page so that this post can be seen in context.

3 recorded likes for this post.

Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

DIBO
February 01, 2025, 21:52:00 GMT
permalink
Post: 11819330
Originally Posted by RatherBeFlying
4. The CRJ crew was left out of the information loop. I have a dedicated traffic display on the top of my glider panel which shows ADS-B and Flarm traffic. A similar display would have enabled the CRJ crew to monitor traffic and get the hell out of the way when necessary.
In addition to previous post on the differences of TA & RA's (which were inhibited at that moment), No they were not left 'out of the loop', but they use their TCAS displayed info, as much as you use your Flarm display when on short final.
From the 'Mil' thread:
Originally Posted by 212man
I take it you are unfamiliar with glass cockpits and Navigation Displays? A couple of examples of the CRJ ND - the TCAS Traffic Advisories are the blue diamonds, with altitude difference:



Subjects ADSB (All)  CRJ  TCAS (All)  TCAS RA

Links are to this post in the relevant subject page so that this post can be seen in context.

No recorded likes for this post (could be before pprune supported 'likes').

Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

FullWings
February 01, 2025, 21:58:00 GMT
permalink
Post: 11819334
Originally Posted by Chesty Morgan
Airline pilots do not, as a matter of course, avoid TCAS traffic unless given an RA, TCAS is notoriously inaccurate laterally, we will try to acquire traffic visually and may then react IF we can.

Also depending on the range selected on the TCAS or ND display you might get a load of garbled nonesense.
Yep, as you may be manoeuvring into a collision if you try and do it off the relative positions on the ND.

Also, with any kind of warning system, they lose effectiveness with the more that they go off. A full-blooded TCAS RA is, thankfully, pretty rare on an individual basis (I\x92ve had 3 over 30 years, two in the USA) and is trained and practiced regularly. The CA/STCA that ATC received might have been the 27th of the day in that airspace for all we know, given the traffic levels and the routings in and out of DCA and criss-crossing the area, plus they did have confirmation of visual acquisition which was now the sole means of separation.

Subjects ATC  DCA  Separation (ALL)  TCAS (All)  TCAS RA

Links are to this post in the relevant subject page so that this post can be seen in context.

1 recorded likes for this post.

Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

CayleysCoachman
February 01, 2025, 22:34:00 GMT
permalink
Post: 11819350
That’s an awfully cluttered display, chock-a-block with information with no salience whatsoever. For many years, I flew a lovely large piston twin, being passed down almost from one owner to the next, with the aircraft, until its last owner installed acres of Garmin glass. I could no longer perceive the propeller RPM with sufficient granularity; the fuel flows were obscured, the whole place became like Blackpool illuminations, and, as I was fundamentally only flying it for my own pleasure, I stepped back.

Urgent information needs salience in displays and suitable attention-getters, but in that regard, proximate traffic near an airport could be given greater prominence, then to be lost in learned noise. TCAS is not the answer to this collision. I’m increasingly reminded of the term, ‘defensive controlling’. Yes, you expect to have vertical separation if the climber stops at its cleared level, but why not give it a five degree heading change, not to achieve any kind of separation, but just to make sure they don’t hit if it busts….

The transfer of responsibility to the helo crew here was entirely legitimate, but also created the single point of failure which led to a collision, and that was foreseeable.

Subjects Separation (ALL)  TCAS (All)  Vertical Separation

Links are to this post in the relevant subject page so that this post can be seen in context.

4 recorded likes for this post.

Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

NIBEX2A
February 02, 2025, 15:41:00 GMT
permalink
Post: 11819865
Once again, looking at the safety reports below. How many of these may have been caused by the helicopter having the wrong aircraft in sight when applying visual separation?

Safety reports, if assessed and promulgated correctly, act as another line of defence. They identify any deficiencies in procedures which may have been overlooked (or underestimated) in the original procedure safety assessment.

Hopefully the crash investigation will delve into these aspects to identify what action was taken on receipt of the reports below by the respective organisations.

I found it chilling to read how many factors associated with this accident had repeatedly occurred and been reported over the previous 20+ years. I’ve condensed the reports [see spoiler- mods] and highlighted in bold many of these deficiencies, identified by pilots.

Common Themes
  • Collision Avoidance taken on helicopters supposedly visually separating from the traffic.
  • Helicopters deviating from their cleared tracks or levels.
  • Helicopters on different frequencies
  • Lack of traffic information on conflicting traffic.
  • “Normalisation” of these incidents.
Multiple comments from experienced aircrew that these procedures were an accident waiting to happen. …………

Spoiler
 




Last edited by Saab Dastard; 2nd February 2025 at 17:15 . Reason: Make it legible

Subjects ATC  Accident Waiting to Happen  Circle to Land (Deviate to RWY 33)  DCA  FAA  Frequency 119.1  Separation (ALL)  TCAS (All)  TCAS RA  Visual Separation

Links are to this post in the relevant subject page so that this post can be seen in context.

No recorded likes for this post (could be before pprune supported 'likes').

Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

uncle_maxwell
February 02, 2025, 16:12:00 GMT
permalink
Post: 11819886
TCAS enhancement?

Instead of no RA below 500ft (or whatever the floor is), how about telling one conflict to climb and the other one to \x91not climb\x92? \x91Not climb\x92 could then be understood (and trained) to mean \x91descend a little, terrain/aircraft/wx permitting or fly level\x92. Lots of ifs and buts, spurious warnings, limitations for when 3 or more conflicts, TCAS vs. GPWS considerations etc. but perhaps worth a thought.

Subjects TCAS (All)

Links are to this post in the relevant subject page so that this post can be seen in context.

No recorded likes for this post (could be before pprune supported 'likes').

Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

PPRuNeUser134364
February 02, 2025, 16:35:00 GMT
permalink
Post: 11819905
I know I'm fighting a losing battle but here goes.....

Originally Posted by DespairingTraveller
I'm struggling to make sense of the numbers being bandied about here. Apparently the NTSB has said that the CRJ was at 375 feet,

But from the beginning, various plots have shown the collision occurring in mid-river. A little work with Google Earth will show that the extended 33 centre line reaches mid-river about 3,300 feet from the aimpoint of runway 33. A 3 degree glideslope and some trig will put it at 175 feet at that range, with obvious implications. 375 feet would be a big error with not much more than half a mile left to run.

What am I doing wrong?

Also, helicopter route 4 hugs the eastern bank of the Potomac until Goose Island and doesn't cross to the western bank until Wilson Bridge. So why did the Black Hawk perform a 45 degree right turn while still abeam DCA? (See, e.g., post #25) Was it intending to route direct to Fort Belvoir, ignoring the heli routes? (I think I've seen it was operating out of Joint Base Anacostia en route to Fort Belvoir, so the fact it was still abeam DCA must have been more than obvious.)

Puzzled.
What you are doing wrong is making guesses based on incomplete/inaccurate data that is in the public domain.

Assuming the NTSB figure of 375ft is correct, you still need more info for it to mean anything. Was that the AGL, AMSL or SPS height/altitude?
How accurate are the 'various plots' that indicate the collision occurred mid-river? They may be right; they may not be.
Was the CRJ on final or was it still positioning to final? If it wasn't on final then the trigonometric calculations of what height it should be at might not be correct.
What official evidence is there that the Blackhawk made a 45 degree turn, or could that be a data error in the publicly available information?

In summary what I am saying is that, despite all of the internet sleuths plotting tracking data, none of it is official and it is all subject to various errors. Whilst interesting to form an understanding of the circumstances, it can't be assumed to be accurate to within a few feet (vertically or laterally).

Originally Posted by JohnDixson
Regarding UH-60L altimeters:
All UH-60 A and L Army aircraft incorporated the APN 209 radar altimeter. Our Sikorsky tech fellow for Avioics/electronis reports the accuracy in this area is 1-2 feet. The radar altimeter position in the instrument panel is just to the right of the attitude indicator and its top matches the top of the attitude indicator. The barometric altimeter is immediately below it.
Both pilots have the same setup.
That 1-2 feet error would be a theoretical accuracy. The readout in the cockpit would be subject to significant errors during turns/pitch changes etc; without knowing the exact installation on a Blackhawk, it might also unlock based on the surface conditions. More importantly, the ATC instructions would probably be based on an altimeter setting and not Rad Alt.

Originally Posted by uncle_maxwell
Instead of no RA below 500ft (or whatever the floor is), how about telling one conflict to climb and the other one to \x91not climb\x92? \x91Not climb\x92 could then be understood (and trained) to mean \x91descend a little, terrain/aircraft/wx permitting or fly level\x92. Lots of ifs and buts, spurious warnings, limitations for when 3 or more conflicts, TCAS vs. GPWS considerations etc. but perhaps worth a thought.
How would that have worked in this scenario? Who do you think should have been directed by TCAS to do what? Does the Blackhawk even have TCAS?



Subjects ATC  Barometric Altimeter  Blackhawk (H-60)  CRJ  DCA  NTSB  Radar  Route 4  TCAS (All)

Links are to this post in the relevant subject page so that this post can be seen in context.

6 recorded likes for this post.

Reply to this quoting this original post. You need to be logged in. Not available on closed threads.