Posts about: "Flight Safety Foundation (FSF)" [Posts: 5 Page: 1 of 1]¶

2008, a Spanair MD-82 crashed in a similar way after liftoff in Madrid. Final report Spanair .Main cause: The pilots did not configure the airplane according to checklist and took of with zero flaps and slats. Contributing: previous maintance was disabling RAT heating (MEL if not flying into icing conditions) which somehow inhibited electrically the takeoff configuration warning. I am not implying in the least that such a thing happended to this Air India crash. I just mention it as a proof that some *minor* quirks can contribute to an accident (i.e. disturb FADEC, TCMA logic, you name it) . Modern aircraft software logic is even more complex than the wired logic of an MD-82. But still: all "IF so and so THEN so and so " code can produce weird results if the conditions are corrupted or delayed by data communication lags. And according to a witness, there were some electrical quirks on the previous flight and possibly some maintenance thereafter. Again not implying any wrongdoing.

- at Minus 8 feet (A Significant Disservice to the TCMA's G/A sensing?)
https://asn.flightsafety.org/reports...738_TC-JGE.pdf

The radio altimeter

During the approach, the left radio altimeter system indicated -8 feet , although the aircraft was at a considerably greater height than that. The Board\x92s investigation has not uncovered a reason for this change in the radio height to -8 feet.

A Boeing 737-800 (flight TK1951) operated by Turkish Airlines was flying from Istanbul Atat\xfcrk Airport in Turkey to Amsterdam Schiphol Airport, on 25 February 2009. As this was a \x91Line Flight Under Supervision\x92, there were three crew members in the cockpit, namely the captain, who was also acting as instructor, the first officer who had to gain experience on the route of the flight and who was accordingly flying under supervision, and a safety pilot who was observing the flight.

There were also four cabin crew members and 128 passengers on board. During the approach to runway 18 Right (18R) at Schiphol airport, the aircraft crashed into a field at a distance of about 1.5 kilometres from the threshold of the runway. This accident cost the lives of four crew members, including the three pilots, and five passengers, with a further three crew members and 117 passengers sustaining injuries.

Shortly after the accident, the initial investigation results indicated that the left radio altimeter system had passed on an erroneous altitude reading of -8 feet to the automatic throttle control system (the auto-throttle). In response to this, the Board had a warning sent to Boeing on 4 March 2009. This asked for extra attention to be paid to the \x91Dispatch Deviation Guide\x92 for the Boeing 737-800, which is a manual of additional procedures and warnings for maintenance crews and pilots to consult before the aircraft is flown. This warning, which was added in 2004, states that with radio altimeter(s) inoperative, the associated autopilot or auto-throttle must not be used for the approach and landing......

More GRIST for the electric 787's software Glitch-Mill? (see my prior post above)
Not really "INOP" if it's feeding in -8 feet?
For those unfamiliar with this accident, the RADALT flaw caused the auto-throttle to enter its "flare/retard" mode quite early in the approach and the aircraft stalled into a field well short. I am not sure how one could extrapolate this into a post-take-off TCMA equivalent Ground/Air misadventure. Radar altimeters have considerable authority when it comes to CAT 3 ILS ops. It has an interface with the EEC, but to what extent?

The entire autoflight, autothrottle, and radio altimeter scheme for the 787 was developed many decades after the system at play in that 737 incident, and I expect that modern rules on hazards and misleading information would not allow a system as described in that report to be certified in the 787 era.


There are many faults in RA systems that can result in incorrectly low altitude displayed. The report for example discusses antenna corrosion. RA LRUs going all the way back to the 1960s had several internal monitors that would drive "flag" and "autoflight enable" output discretes, but a loss of antenna isolation could sometimes result in a "locked" low altitude indication without a fault detected. In that era of federated avionics, aircraft equipped with dual RAs usually also had a separate comparator box that would compare the outputs and alert the crew if the values diverged - even if the RA LRU hadn't "flagged" the indicator. I am surprised that comparator output wasn't checked by the autothrottle system.


I am curious if anyone knows the backstory on the 787 being equipped with two RA systems vs three on previous Boeing widebody models.

I've been in a similar situation once when the Twin Otter I was flying was hit by a surface-to-air missile . I put out an initial Mayday call as soon as I had the heading & altitude under control (that took about 5 seconds) but before taking any other actions. I didn't have any intention of entering into a long conversation when I made the call, I just wanted dispatch to know that we had a serious problem - in case we didn't come out of it alive.


Fortunately, we did come out of it alive, and after completing all the appropriate checklists, picking a nearby airport to land at, and lighting up a cigarette, I called dispatch back and explained the situation.

To me, it is understandable that the pilot made a Mayday call.

Many are maintenance or production test flights. Someone commented upthread that every Boeing widebody built gets the RAT deployed on its first flight, and I imagine some maintenance procedures require it too.

ASN has a section on electrical power incidents: https://asn.flightsafety.org/asndb/cat/ACSE

In particular try these:

https://assets.publishing.service.go...009_G-EZAC.pdf
https://asn.flightsafety.org/wikibase/233343
https://asn.flightsafety.org/wikibase/219748
https://asn.flightsafety.org/wikibase/34357