Wednesday, January 4, 2017

SU1008 UMKK/KGD Kalingrad A321 VP-BES Runway 24 Departure

An Aeroflot A321departed runway 24 at UMKK Kanlingrad on Jan 03 2017 20:54.

Weather reports include forecast medium braking in wet snow, poor visibility, low ceilings with thunderstorms in the area, and a heavy crosswind.  The airplane ended up on the right side of the runway, about 5,500 feet from the runway threshold.  The crosswind was from the right, so the airplane deviated into the crosswind.

Runway 24 is 8202 feet long at 31 feet MSL.

flightradar24,com ADS-B data for SU1008

Location: UMKK
Latitude: 54°53'24"N - Longitude: 020°35'42"E.
Magnetic declination: 6.04°E
Sunrise: 07:01 UTC
Sunset: 14:23 UTC
Report emitted the day: 03, time 21:00 UTC
Tuesday 3 January 2017 23:00 local time.

Wind: True direction = 180 degrees, speed: 7 m/s (14 knots) (25 Km/h).
Runway 06, length 8202 feet, altitude 43 feet: Cross Wind 6 MPS Right - Centerline Wind 3 MPS rear.
Runway 24, length 8202 feet, altitude 31 feet: Cross Wind 6 MPS Left - Centerline Wind 3 MPS front.

Minimum horizontal visibility: 1700 m.
Maximum horizontal visibility: 200 m direction North East.
Runway 24, touchdown zone visual range is 0600 meters (1969 feet).

Weather: Strong Showers of Snow Rain .
Clouds: Broken sky (5-7 oktas), at 300 feet above aerodrome level (91 meters).
Clouds: Broken sky (5-7 oktas), at 1400 feet above aerodrome level (427 meters), cumulonimbus.
Temperature: 0 degrees Celsius (32 Fahrenheit). Dewpoint: 0 degrees Celsius (32 Fahrenheit). Relative humidity 100 %. Wind Chill: -6 degrees Celsius (21 Fahrenheit).

QNH (Sea-level pressure): 991 hPa (29.26 inches).

Runway state:
Runway 24 (or 24 Left): wet snow, contamination 51% to 100%, depth of deposit not reported, friction coefficient 0.32.
No significant changes expected in the near future.

Qfe 990 equates to pressure altitude of 641 feet.

Friction coefficient reported at 0.32 coupled with wet snow would predict medium braking, runway condition code 3 most likely.

A relatively low pressure coupled with reported thunderstorms, a significant cross wind, in poor visibility, at night.

Looking at the final approach, the ADS-B reports stop short of the runway itself. The last report is over 2000 feet from the threshold.  I have assembled the data to evaluate glide slope tracking.  The reported pressure altitude must be compensated to yield a comparable above ground level (AGL) measurement.  Qfe is reported at 990 hPa, or about 641 feet pressure altitude.  

If plotting this offset, it appears that SU1008 was under the glide slope until nearing the threshold.  However, this plot does not reflect the expected glide slope capture.


Putting in 150 foot offset (as modeled, this would be error in reported pressure altitude) yields a more likely glide slope capture, but renders the final stages above the glide slope.  The speed excursion is not fully explained, but would appear in this case to be poor control.

Qfe=497 press altitude
There appears to be a speed upset (or loose control) and the airplane appears to be drifting above the glide slope slightly.

Looking at the same flight (SU1008) from a couple of days earlier shows the same trends.

Looking at the flight S777 (where data is available) prior to SU1008 on 3 Jan (two hours earlier), shows stable speed control and a slight rise above the glide slope at the end of the approach.  S777 reported no issues.

Qfe=391 press altitude
In all three examples, I adjusted the runway pressure altitude to trigger a normal glide slope capture. I may not have accurately calculated the above ground level (AGL) by this adjustment (e.g. whole altitude profile shifts, which could realize less or more deviation from glide slope than pictured).  The inability to provide exact AGL is a weakness in ADS-B pressure altitude reporting.  Similarly, ADS-B reports ground speed, which add a wind component to true airspeed, making absolute airspeed measurements elusive.

SU1008 would have landed long by about 2,000 feet past the planned touchdown zone if it was 120 feet above the glide slope on short final.  The final resting place and damage would  suggest the airplane did not land excessively long, but must have lost directional control after touchdown.  There is no ADS-B data to reveal any more detail.

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 35 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 PP848, ARINC 791, and PP792 standards and characteristics. 

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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