News Polish president dies in plane crash

[Andre]

Sorry for ressurecting this old one. It appears that we never finalized it.
The essential mistake was almost certainly a very old mistake, a wrong altimeter setting.

From the report (p 14):

...A moment later, CC set his WBE-SWS altimeter to the standard pressure of 1013 hPa. It caused TAWS to receive wrong data and, in effect, the system inhibited generation of warnings, assuming that the aircraft was higher up than in reality.

So as altimeters are working on local barometric pressure, it has to 'know' the ground pressure. There is a dial to put that in. However there are three different settings QFE, pressure for field elevation, giving 0 at ground level, which is hardly used anymore (in the west), QNH, pressure Nautical Height, (sea level) giving the field elevation on the ground, which is used for low altitude parts of the flight, and standard altimeter setting (1013.25 hPa or 29.92 inches) which is used above a certain altitude (transition height), obviously to ensure altitude separation between flights, all being on the same setting.

In the log you can read that the altimeter was indeed changed both in the climb to standard setting and later in the descend to local QFE(?), which was much lower at the time.

p: 213:

At 0628:47, at an altitude of 2,176 m, the aircraft commander‘s VBE-SVS altimeter was switched from standard pressure to another setting (judging by the discussion between crew members, to 993 hPa, which was the barometric pressure at airfield level, and from that point barometric altimeters read altitudes in reference to the runway)

But then suddenly:

At 0640:14.5 at an RA altitude of 366 m (297m above airfield level, at a distance of 4,768 m from RWY 26 threshold), at a speed of 309 km/h, the VBE-SVS altimeter of the aircraft commander was switched to standard pressure of 1,013 hPa.

Immediately afterwards, at 0640:15 – at RA altitude of 366 m, 295 m above airfield level, at 4,724 m from RWY 26 threshold, TAWS stopped generating the TERRAIN AHEAD message.

And that caused the accident almost certainly. Obviously the person who made that mistake was under great stress. He checked the altimeter setting, did not mentally process the indicated value maybe and changed it maybe to a setting that was familiar to him. A 20 hPA error equals 540 feet/ (165 meter) 28 ft per milibar, the wrong way. Obviously that was enough to make the accident unavoidable.

 

[Czcibor]

That's easier said than done sometimes, arildno - whether the pilot is in charge or not, the politician still has the power to destroy their career.

The pilot who lead this tragic flight was the second pilot in the flight to Tbilisi. One of presidents men (Gosiewski) actually tried to prosecute the first pilot for cowardice and refusal to perform presidential order.

Our prime minister (yes, Tusk is a more sensible person with rather unfriendly attitude towards Kaczyński brothers) actually awarded the pilot for this refusal. However, from perspective of long term job security of pilots... that still wasn't tempting.

Keep in mind that Poland is now full of conspiracy theories, and Jarosław Kaczyński is actually trying to win next election by implying some kind of plot.

 

[Andre]

The pilot who lead this tragic flight was the second pilot in the flight to Tbilisi. One of presidents men (Gosiewski) actually tried to prosecute the first pilot for cowardice and refusal to perform presidential order.

This is a very common dillemma. When I was asked to rewrite our air force rules book, this was by far the biggest [STRIKE]PITA[/STRIKE] bleeb. Army generals want to order the aircraft captain to go where they want to go. One of the rules that is written in blood (of many and counting) is that the captain of the aircraft decides what is safe and what is not safe and nobody shall ever challenge that. Not even your favorite local god.

There should have been no stress on this captain for his carreer for whatever he was going to decide.

And remember: a superior pilot uses his superior judgement to avoid situations that require his superior skills.

 

[dlgoff]

The essential mistake was almost certainly a very old mistake, a wrong altimeter setting.

I don't understand why, even in small planes, you wouldn't go the cost for a Radar Altimeter.

 

[Borek]

They had the radar altimeter, but they were not aware of the way the land is formed on the approach. There is a wide and shallow valley there. So while the terrain around the airfield is generally flat, when you are approaching it raises much faster than expected. That means barometric altimeter was giving better information.

I don't remember report details now and I don't plan on rereading it, but this slope was one of their problems - I think the second pilot was reading indications of the radar altimeter, which gave them feeling of false safety, as they thought they were tens of meters higher than they were in reality. Once the land raised they got very low very fast and the situation got critical immediately.

 

[dlgoff]

I guess I was somehow thinking the RA values in the report was from a ground based measurement.

 

[Borek]

In Poland today National Geographic is going to air "Death of the President" for the first time. This is part of their Mayday series.

But I won't be able to see it.