Friday, October 12, 2018

Close Calls Coming (TG679) and Going (IX611)

ADS-B OUT data broadcast coupled with machine learning can create a great enhancement to aviation safety. Flight Operations Quality Assurance (FOQA) was conceived as an anonymous means to reveal unsafe trends. The post-flight evidence would guide training and awareness, not personal vendetta. With ADS-B, the alerting can be done in real-time; the trends recognized as they are occurring.

IX611 Takeoff normal (A) and accident (X)

SAVE is still the basic concept.  ADS-B tracks from the past develop expected behavior. From Machine learning, recognize unsafe deviations as they develop. The challenge is timely alerting and pilot interface.

Cameras everywhere?

I used to see a weekly report of all the aviation incidents around the world.  Probably less than 5% make the news, because they were close calls. I will just mention that a lot of people seem to think hiding in an airplane is a good idea. One of the situations that seemed to repeat was loss of structural components (panels in varying forms).  The flight crew could not see the damage from their vantage point. Just then, cameras were gaining favor as a passenger amenity, and the 777 was going to use them for taxi guidance.  

Why not put cameras all around the airplane? Then the flight crew can scan for any missing parts directly.

What came clear is that the challenge is what would a pilot do with the knowledge. Yes, awareness is good. But is a diversion, an emergency descent, a ditching in order? Thus, the reliance on instruments and procedure. It is not a problem, until is a problem.  It goes to the same logic with alerting the pilot to the loss of a backup system.  It is not a problem, until it is a problem. 

Investigations using ADS-B Data

PLEASE TAKE NOTE: Accident investigation is a serious business that involves a private and deliberate process.  Using ADS-B data to comment while an ongoing investigation is done carefully with intent to advance the benefits that ADS-B technology may bring - and as a result it does provide some insight into the "what happened" question. Assessing cause or blame is for an investigation with a complete and fair evaluation of all of the information. The insights from cursory ADS-B data are hardly of any real consequence, other than satisfying curiosity, while trying to dampen outrageous suppositions, and always with concession from personal lack of information and understanding, and that complete authority lies with the investigators. The public wants to know, ADS-B is a great tool for simple assessment.

TG679 Landing Overrun

From Aviation Safety.Net
Thai Airways flight TG679, a Boeing 747-400, suffered a runway excursion after landing on runway 19R at Bangkok-Suvarnabhumi International Airport, Thailand. 
There were no injuries.  
Weather about the time of the incident (22:58LT / 1548Z) VTBS 081600Z 21012G22KT 3000 TSRA FEW008 FEW020CB BKN030 BKN080 25/22 Q1012 RERA BECMG TL1620 5000 TSRA  
VTBS 081530Z 16006KT 7000 -TSRA FEW020CB BKN030 BKN080 25/22 Q1012 TEMPO TL1600 5000 TSRA  
VTBS 081500Z 23009KT 190V270 8000 -TSRA FEW020CB SCT030 BKN080 25/23 Q1012 NOSIG

Notable is the 10 knot gust component (increasing headwind) in the METAR.

Flightradar24 recorded data stopped on short final.

Comparing the overrun to prior approaches showed nothing amiss, the path in space, and speeds, all appeared normal.


Whatever happened to TG679, it happened during the flare and rollout. It is possible that a strong gust caused the plane to float a bit, but there is nothing to prove that was the case.

The ADS-B OUT data ruled out a wind shear or unstable approach as an evident factor. 

The lack of data along the runway precludes any further insight.

IX611 Clips Wall and Antenna Structure on Takeoff

From Aviation Safety.Net
Air India Express flight IX611, a Boeing 737-800, impacted the localizer antenna and an airport wall on takeoff from Tiruchirappalli International Airport, India. The aircraft took off from runway 27 at 01:18 local time. 
Past the end of the runway, the underside of the fuselage hit the localizer antenna and a brick wall, causing severe damage. 
The aircraft climbed to FL360 and proceeded towards Dubai. 
According to a statement from Air India Express the crew reported that all systems were normal. 
After learning from Tiruchirappalli that they might have hit a wall, the flight crew decided to divert to Mumbai. 
At that time the flight was well over the Arabian Sea. The aircraft landed safely at 05:38 local time.
METAR Weather report:19:30 UTC / 01:00 local time: VOTR 111930Z 00000KT 5000 BR FEW018 SCT100 27/24 Q1008 NOSIG20:00 UTC / 01:30 local time: VOTR 112000Z 00000KT 5000 BR FEW018 SCT100 27/24 Q1007 NOSIG
Winds were not a factor, nor any weather aspect apparently.

Flightradar24 ADS-B data allows comparing the accident takeoff to a prior takeoff.  A normal takeoff (A) is compared to the incident flight (X) in the following graphic.

What is apparent is that the takeoff started out normally, to a speed of about 130 knots. Inexplicably, the airplane seemingly only sluggishly accelerated well beyond the runway design, becoming airborne only after striking a wall and antenna structure.

Stay tuned!

Peter Lemme

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Follow me on twitter: @Satcom_Guru
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Peter Lemme has been a leader in avionics engineering for 37 years. He offers independent consulting services largely focused on avionics and L, Ku, and Ka band satellite communications to aircraft. Peter chairs the SAE-ITC AEEC Ku/Ka-band satcom subcommittee, developing ARINC 791 and 792 characteristics and contributes to the Network Infrastructure and Interfaces (NIS) subcommittee developing Project Paper 848, standard for Media Independent Secure Offboard Network.

Peter was Boeing avionics supervisor for 767 and 747-400 data link recording, data link reporting, and satellite communications. He was an FAA designated engineering representative (DER) for ACARS, satellite communications, DFDAU, DFDR, ACMS and printers. Peter was lead engineer for Thrust Management System (757, 767, 747-400), also supervisor for satellite communications for 777, and was manager of terminal-area projects (GLS, MLS, enhanced vision).

An instrument-rated private pilot, single engine land and sea, Peter has enjoyed perspectives from both operating and designing airplanes. Hundreds of hours of flight test analysis and thousands of hours in simulators have given him an appreciation for the many aspects that drive aviation; whether tandem complexity, policy, human, or technical; and the difficulties and challenges to achieving success.

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