"According to newspapers, the officials were supposed to say, that up to distance of 2 km (from runways threshold, or touchdown zone), everything looked fine and correct - the aircraft was 100 m above runway threshold elevation (even though the MDH - minimum descent height was 120 m). The aircraft than increased the rate of descent to 6-7 m/s. It is possible that the rate was even higher in later stages although it was not registered by the approach monitoring radar which, unlike PAR, has a delay 5 seconds."
"Сергей, you have done a great job. Based on available information and your hard work, only two primary reasons may be concluded. (1) Intentional descent by the crew below MDH, using primary RA and excluding baro altimeter from the scan"
"(2) Airspeed lost during level-off at 100 m above runway threshold elevation following by the development of high sink rate, initially not observed by the crew due to RA indications affected by the lowering terrain. There was not enough time and spare altitude to recover especially considering now rising terrain, In any case no help from EGPWS available, due to lack of XUBS in EGPWS database. If EGPWS was inhibited to avoid TCF warnings, also the RFCF warnings and altitude callouts were absent"
"If the information is true, that the aircraft was at 100 m height above threshold, at the distance of 2 km (from the runway threshold, I guess), then its altitude was 355 m AMSL (above mean sea level)."
"Anyone can verify that Smolensk airfield was not in the EGPWS database by entering its ICAO code XUBS into search window of EGPWS Mk. VIII airport database:
MK VI & VIII Airport Search - Honeywell . This answers the question why the EGPWS did not warn the crew. It would give TCF (Terrain Clearance Floor funtion) warnings after descending through 700 feet (about 210 m) AGL above ground level, so the crew ignored the warnings or even inihibited EGPWS audio warnings to avoid distraction by them."
"For comparison one may enter EPWA (Warszawa/Okecie) and see the results. Inhibiting EGPWS audio to avoid "distracting" or "nuisance" warning casued that no RA altitude call-outs were inhibited as well. RFCF function was not available since the airport was not in the EGPWS database (because it was not measured according to WGS-84/PZ-90 and was not published in Russia AIP). More on that here:
http://www51.honeywell.com/aero/comm...ance_Floor.pdf with a classic example"
"The Presidential Tu-154 which crashed on 10th of April will become another sad example, why all airports should be in EGPWS database, even though it was not the primary reason for the crash - just a contributing factor."
"Regarding
http://www51.honeywell.com/aero/comm...ance_Floor.pdf "Height Above Field Alert Envelope refers to RFCF protection"
"Anybody can learn more about EGPWS by reading the EGPWS Pilot Manual:
http://www51.honeywell.com/aero/comm...VIII_EGPWS.pdf"
"Сергей, I do not accuse anybody. It is expensive to have the airport and surrounding obstacles measured in WGS-84/PZ-90. However the aircraft operator should consider before any operation if it is safe to land at such an airfield, especially in IMC, with low visibilities and ceilings. The operator shoulld have special procedures for such situations. And the crew should never, ever ignore EGPWS warnings or inhibit the EGPWS audio system."
"I would add however, that in most countries, including Poland, even small VFR-only airfields, which are published in AIP Poland, has been measured in WGS-84 and are included in EGPWS database providing the runway has suf ficient lenght. Since the airfield was used by state aircraft, including Russian state aircraft, it was not senseless to have it measured. But like I said before, it was kind to allow the use of airport, and the aircraft operator (Polish Air Force) should by thoroughly familiar"
"with all the limitations. I do not suggest that PAF should demand anything, and the airport management was not obliged to provide any extra facility or measures, including WGS-84/PZ-90 measurements. BTW, I know that measurements of all airports in Russia iaw PZ-90 has been on the way for some time. This is good for safety."
"This is just frustrating for a pilot, when he or she flies with EGPWS, and yet the great capabilities of this life-saving device are compromised, in case of airports which are not in the EGPWS database, and yet they have legal instrument approach procedure and can be used legally in IMC. This frustration is also mine. The EGPWS creators didn't envision such a possibility."
"Yet the decision is left in the hands of aircraft commander - to inhibit EGPWS audio warnings, or listen the nerve-wrecking "Too low! Terrain! Too low! Terrain!" throughout the last part of procedure flown in IMC, close to the ground."
"There is something very helpful in situation like that. It is called TLS (
Transponder Landing System - Wikipedia, the free encyclopedia), and is compatible with any airborne ILS avionics. A mobile version can be deployed in less than 3 hours, and gives the same capablities as conventional ILS. In certain aspects it is even better system. PAF should have one or two such system to be used on ocassions like that in Smolensk. But I'm just a pilot. As always, the governent knows "better"."
"tp://www.anpc.com/prod_mobile.cfm
However, it is not clear to me, whether Russians would allow for such a mobile installation to be deployed at their airfield in Smolensk for several days. I am not aware if Russian version of TLS (if any is available) is compatible with ILS/TLS. Of course TLS needs flight inspection - it takes a few hours. And if not TLS, then JPALS:
Joint Precision Approach and Landing System - Wikipedia, the free encyclopedia . Maybe it's even better than TLS. PAF definitely need one."
"One remark on EGPWS - this is known now, that TAWS manufactured by Universal Avionics Systems was installed on board and not the Honeywell's EGPWS. Nevertheless the problem has been the same. XUBS airfield has been not in the database, causing initially nuisance warnings during approach, and therefore TAWS had been likely inhibited by the crew, or the warning had been ignored almost to the end by the crew (except for the very last RA altitude callouts)."
green line vertical speed 3m/s red 6m/s
