Posts about: "ADSB Out" [Posts: 39 Page: 1 of 2]¶

The military helicopter did have a Mode S transponder, but no ADS-B out. The CRJ had a standard transponder with ADS-B out. In all my data sources, the helicopter is visible but only as an MLAT target, so its position in all the flight tracking feeds (ADSB Exchange and FR24) is inferred via time of arrival difference of the Mode-S signal at various receiver stations in the area (i.e. within 200-300m position precision).

TCAS however can operate off Mode-S signals alone, but as others have pointed out, during the late approach phase of a flight, TCAS RA is inhibited (but the target would have caused a TRAFFIC alert still and shown yellow/red on the TCAS display). The helicopter crew assuring the frequency they have identified them would have led them to believe they were cutting it close but will avoid.

It would have been a luck of the draw situation for the CRJ crew to see and avoid the helicopter. It's very hard to see a couple of light points moving against a sea of ground point lights at night. Assuming the CRJ had its logo light on, their only chance would have been for the helicopter crew to spot them (which they claimed they did?)

If the helicopter had the same displays the airplane down the road I rent has they would have seen that the plane they were looking at farther off (if this is the case) was not the one that was close to them and getting closer. I get a military aircraft may not have felt the need for ADS-B Out, but a portable unit showing traffic IN would seem almost a must-have around DCA.

Fairly confident (and reported earlier) that the Blackhawk only has Mode S, so no ADS-B. Mode S may report less than ADS-B which means that position updates can be (but not always) significantly slower than ADS-B out. I also believe that for RA to work both aircraft would need to have both ADS-B In and ADS-B Out so that 2 way data communication can take place.

That's incorrect. TCAS II can communicate to achieve coordinated RAs with Mode S in each aircraft. If a threat aircraft has only Mode 3/C (and therefore no TCAS) then an uncoordinated RA can be generated against it. If it has only Mode 3 then it will be shown without altitude information and can only generate a TA on another aircraft's TCAS.

Allow me few comments based on a long experience with TCAS evaluation et deployment .

1) TCAS II can still be improved : No end of the story by now , no version 8 in the pipeline . We spent millions and years on getting 7.1 accepted .. and even not everyone mandates it .

2) ADS-B gets already saturated , add TCAS type system and it will be .But developing a new Anti-collision system based on ADS-B is in the pipeline however it will; mean ASD-S be out mandated for every flying aircraft , including military . Here is your problem . Some military aircraft cannot be retrofitted , no space ..

3) interoperability .? No , 2 completely different systems , TCAS is analog 1970 technology ,

4) TCAS RAs on approach? you mean below 1000 ft ? No , in our scenario here , with the Blackhawk climbing , the logical RA would be a descent RA for the CRJ ,, you want a Descent RA at 300 ft ?

The only solution I personally see is airspace segregation based on equipment . Class A, B and C restricted to aircraft carrying ADS-B out and TCAS equipped , and both Working and on the MEL as no go item s ( not the case today ) Waiting for AOPA and ATA remarks

i thought ADS-B was already required for Class B or under it. It certainly is for DCA. No way are you convincing anyone to put TCAS in a C-150 when they already ponied up for ADS-B.

I was taking Military , and here in DC airspace Class B you had one aircraft without ADS-B. out.( not that it would have changed anything ,) but if you want to devise /create a performant CAS using ADS-B it starts there .
Then there is the question of the C150s, you raised , of course no TCAS, we are talking ADS-B out, but even then, do you really want to have them anywhere near the approach path of a major busy airport airspace to start with ?

The military somehow exempted themselves with the results we see now.
I was a frequent visitor to DCA in C-150s and C-172s pre 9-11, it was a nice way to get to the city for dinner from the island I live on. Unless the airlines start buying their own private airports there is no sorting out of airplanes like that, public airports are for everyone with an airplane (9-11 bullcrap excepted). They would do "river tours" back then too, you got a trip up and down the Potomac with some great sightseeing. Back then airplane ramp fees were less than you could end up paying to park a car

Apologies on not using accurate terminology wrt being stepped up solutions but;
the technology is available to stop dual transmissions, even a warning light in the cockpit (ATC station).when simultaneous transmissions are being made would help safety.

On the collision avoidance technology the CAA gave a grant of \xa3250 towards the cost of approved FLARM devices one of which I have - XC TRACER MAXX - which also has FANET.

The swiss invented FLARM nearly 30 years ago and marketed it at cost; it has been obligatory in France for glider operations for the last decade. According to the CAA website it is better than the ADS-B out.

The telecommunication industry has come a long way from the necessity of climbing into the electrical bay and re racking or thumping a radio module but basic cockpit radio procedures haven’t.

What appears to be also relevant is the language and associated phraseology; there was a narrow airmiss in Dublin between an executive jet on take off and a private helicopter pilot caused by ambiguous crossing clearance issued - cross behind the rolling aircraft IIRC which the helicopter pilot took to mean the aircraft rolling down the runway after landing whereas the controller meant the executive jet about to roll; the copilot stuffed the stick forward after take off and passed underneath helicopter.

In this accident I presume that all were Americans; flying around a southern French airfield the controller standard can be diabolical.

Dumbo Question 1.

How would the successful transmission of ADSB Out information by the Blackhawk have changed the outcome on January 29?

After watching the US Congress “grill” the military, FAA and NTSB how could they participate in a conspiracy of silence…

The NTSB will be seen as either very dumb or deceitful or both.

Now what was the number of the Q ANON Pizza shop, I feel like some truth tonight.

Send it to me via Signal. What a joke! The relatives of the crash victims were there to watch the farce.

The small elephant in the room…

Unfortunately, and I hate to say this, I have reached a conclusion beyond those reached by other posters to this forum, to wit:
The US Army, in order to meet its mission requirements, really does not want civilian pilots (commercial or otherwise) to know where its helicopters are. My evidence for this is: The eagerness of the US Army pilots to assume responsibility for seeing and avoiding commercial aircraft; The DCA tower procedures that do not allow civilian fixed wing pilots to hear the conversations between the tower and the helicopters; The Army practice of turning off ADS-B out while on missions and training flights that follow mission profiles (as explained by the USA general in the hearing); The Army's refusal to produce the memo regarding its use of ADS-B to Senator Cruz.
Should the policies adopted by the US Army be regarded as the fundamental cause of this accident?

Dumbo Question 2

Given the extraordinary level of interest in the US Army Blackhawk carriage, activation and transmission of ADSB Out information in the US Congress in the last couple of days, do you think the NTSB could have confirmed (facts) how that information would have been displayed in the cockpit of the CRJ and the ATC TWR cab at Washington DC Reagan?

The small elephant in the room.

ATCDumbo
I'm all ears, excellent point. This focus on ADSB-OUT, and ADSB-IN is really a furphy in terms of this investigation to determine the facts, the whole facts and nothing but the facts.

If 5342 had ADSB-IN then PAT25 not having or not displaying ADSB-OUT could be relevant depending on 5342's cockpit display, the training of the pilots and their scanning.
5342 didn't have ADSB-IN so move along, move along, nothing to see, these aren't the droids you're looking for.

**Caveat. If the TWR display were using ADS-B for their updates and to generate Collision Alerts then the absence of PAT25 ADSB-OUT could be relevant.
But would the TWR ATC even know (or care) whether PAT-25 was ADSB-OUT capable. TWR ATC involves looking out the windows and judging the relative positions of aircraft.

Note: ATC display systems are not referenced in the NTSB Aviation Investigation Preliminary Report. This seems to be a glaring omission. So perhaps the NTSB are either very dumb or deceitful or both.

To further illustrate the focus on ADSB. Figure 1 Google Earth image with preliminary ADS-B data for flight 5342 and radar data for PAT25.
The ADS-B plots are 1 seconds intervals, the radar data are 4 second interval (as stated during US Congress Q&A).
So the focus is on the whizz bang ADS-B kit rather than what the ATC saw on their display.

There is reference to ATC radios, and 5342 was on frequency 119.1 MHZ and PAT25 was on frequency 134.35 MHZ. The ATC could've had them on the same frequency (changed PAT25 to 119.1 MHZ) but this would be abnormal. ATC Voice Switch systems like Frequentis, SITTI and Rohde & Schwarz typically have a frequency coupling, whereby controller broadcasts on multiple frequencies (2 or more) and voice communications on one frequency are heard on the other. In this case, ATC would broadcast on 119.1 MHZ and 134.55 MHZ and 5342 would hear instructions for aircraft on 134.55 MHZ, and PAT25 would hear instructions for aircraft on 119.1 MHZ.

Yes, visual separation is typically used close to an aerodrome where the ATC is applying visual separation to reduce the standard from 3NM to something less, 2NM, 1NM, or even less, depending on the circumstance which includes weather (included visibility), day / night, workload to monitor the separation, plus other considerations such as equipment.

I just wonder how many of the January Route 4 Helicopter plots crossing RWY 33 Approach (post 1346) were the result of ATC issuing a control instruction to change the track to closer to the shoreline or further over water.

Use of Route 4 during RWY 33 Approaches or RWY 15 Departures is possible providing a clearance limit is imposed prior to assigning relevant traffic, positive control instruction(s) and in the case of 5342, advising them of the relative position of PAT25 and that PAT25 would be maintaining separation from them.

Example for Route 4 southbound would be a clearance limit of Hains Point. Helicopter would be released past this point when there is no conflict (nil traffic) or assigned separation to avoid (pass behind). If there is a in-line stream of arriving traffic then Route 4 may not be available.

Sydney KSA has something similar for one of their helicopter routes - BONDI 5 (yep, named after the beach), delays may occur when RWY 07 is in use for DEP, or RWY 25 is in use for ARR. Further, the route is not available when RWY 16 PRM approaches are being conducted. Sydney KSA helicopter routes are in text form - TRACK TO..., TRACK VIA..., EAST OF..., and the INBOUND routes to Sydney KSA have a clearance limit in the clearance. A map display is very useful however it should be based on route descriptions. Perhaps the committee of 17 knows the history of the helicopter routes in and around DCA.

No, I think the US Army policies with regard to ADS-B will be found to be irrelevant to this accident. Brigadier General Matthew Braman is correct in that the US Army, and other government agencies with policing, security and counter intelligence responsibilities do not want their aircraft tracked on FR24 and the like. The MOU is key and may not see the light of day in the public domain. National Security will trump (sorry) other considerations, even safety, especially with so many high profile score buildings adjacent to DCA.

I feel like this ADS-B discussion at political level is just a diversion , either they have been badly briefed by their staff , or they have and are deliberately chosen to raise this in public to shift the blame game somewhere else.
Because , even if the helo had ADSB out and the CRJ an "in " receiver and a CDTI display , what would have happened then ? . The crew would have spotted the Helo, maybe asked ATC what was that , and the reply of the controller would have been something like : " it is a military helicopter on route 4 , has you in sight , passing behind ." and then would you , flying the CRJ , take evasive action or go around after hearing that ? No .
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The primary cause of this collision is airspace design and normalization of deviance over the years. I hope the judges will see that when the trial comes. We should leave the military crew and their grieving families out of this.

I tend to agree with ATC Watchers take on this.
Some people are making out that if the Helicopter had ADSB-out switched on/ activated, then this would never have happened.
Someone correct me if I am wrong but if the Blackhawk has ADSB-out switched on then nothing changes for the CRJ on that night. The TCAS behaves the same, there is no display of the Blackhawk on the CRJ\x92s Nav display\x85..nothing changes. The CRJ crew are still conducting an approach that requires a lot of fast mental processing close to the ground, at night onto a short runway while ensuring checklists/configuration etc is correct. ie they have a high workload. During this high workload phase, \x91the system\x92 has seen fit to allow a single Human ( the helicopter Captain) to be responsible for the separation of the two aircraft visually, at night, in a busy environment while conducting a check, on NVG\x92s.
Is it likey that a single Human, with the sole responsibility, will make a mistake? It\x92s not just likely, it\x92s inevitable, regardless of how sharp and well trained they are, if you run the program long enough their vision, or their SA will fail them and we get what we got here.
The system should never have devolved to the point where one person accepted the responsibility for visual sep 6nm away, at night, in a busy traffic environment while dealing with their own high workload.
The Blackhawk crew had a high workload, the CRJ crew had a high workload, the ATC had a high workload, there was no fat left in the system. Humans make mistakes and any good system will be tolerant of those mistakes.
The system was not tolerant of a mistake, ergo, the system is at fault.

Recognizing that if the only change was ADS-B Out on the helicopter would not have changed things, the use case proposed by the FAA and shown in their promotional materials in support of ADS-B is a helicopter flying in crowded airspace with a display of nearby ADS-B Out traffic. With only half the system installed, it's not going to work.

This is from 7 years ago:

Both crews were set up to fail. Considering the near monthly DCA conflicts between helos and fixed wing over a number of years, the surprise is that a midair didn't happen sooner. The data was accumulating, but nobody caught on in time. Not transmitting ADS-B Out in busy airspace and flying in that airspace with night vision goggles restricting view is a major factor. The lack of ADS-B In in the cockpits is another. Then there's the FAA approval of a helo route with inadequate vertical separation from the 33 approach slope along with a lack of ATC procedure to ensure positive separation between helos and aircraft on approach to 33.

Somehow I doubt that all those responsible for those lapses in oversight were female - quite possibly they were all male.

I really struggle to comprehend why the helicopter not transmitting ADS-B Out is relevant to the accident. What benefit would the other two parties - the CRJ and the TWR Controller gained?
The CRJ didn't have ADS-B IN, and the ATC Surveillance system (radar) doesn't process the data.

DM as required to convince me otherwise.

Back in my post #1385, I briefly mentioned some new info that the NTSB provided at the 3/27 Senate hearing regarding the NTSB’s investigation of the functionality of the 12th AB UH-60 fleet ADS-B systems. Below is the full transcript of the NTSB’s relevant testimony:

Since the DCA accident, the flight tracking apps have shown DC military helicopter flights (PAT, MUSL) to be using ADS-B on a regular basis. However, I can also report that, a couple nights ago, a pair of UH-60s flying Route 9 passed by my house, the second about 5 miles in trail of the first. On ADS-B Exchange the first UH-60 was shown by only a generic aircraft icon with MLAT data. The second UH-60 was displaying ADS-B data. Since it was dark, no idea if these were Mike or Lima UH-60s.