Tag Archives: Aviation Safety

Lufthansa A320 wingstrike at Hamburg

I’ve been receiving a lot of questions dealing with the LH Airbus 320 D-AIQP crosswind landing incident occurred on Mar. 1 at Hamburg airport. For those who don’t know yet what happened, I suggest having a look at the following amateur video that is also available on youtube and liveleak:

Flight LH 044 from Munich was approaching runway 23 under strong crosswinds when it was invested by a gust right before touchdown that raised the right wing leading to an unstable flare. The left wingtip slided along the runway before the engine provided enough thrust for a go around.

Fortunately, despite a lower half of winglet bent inboard and a slat partly damaged, the aircraft was able to perform another approach and land at the second attempt (at 13.55LT), even if there’s no video available of the A320 landing safely (it would have been interesting to see the different approach flown by the PIC after the “incident” with the left wing slightly damaged).

First of all, answering to those who wonder if the pilot is a hero or made a mistake, I think it the video is not sufficient to decide. Hower, the analysis of the available video (and pictures) can suggest a few hypothesis.

Let’s look at the weather conditions at Hamburg. The METAR for the airport at 12.20Z / 13.30LT reports:
EDDH 011220Z 29028G48KT 9000 -SHRA FEW011 BKN014 07/05 Q0984 TEMPO 29035G55KT 4000 SHRA BKN008

The actual wind conditions was 28G48KT (meaning 28 Knots with gusting up to 48 KTS) with a forecasted speed (TEMPO group, that indicates a temporary significant change within two hours from the observation) of 35 KTS with gusts to 55 KTS.

Since the aircraft approached RWY 23, considering the magnetic variation and the actual wind direction of 290°, the xwind (crosswind) component, according to my Jeppesen Model CR-3 Computer, was 25G42KT with forecasted xwind component of 31G48KT.

That said, considering that the demonstrated maximum xwind for the A320 is below 40KTS and that the actual conditions at the destination airport during approach are not known since the METAR is just an average calculation (in order to know the actual wind we should listen to the ATC comms, when the TWR controller read the windcheck to the LH044 before clearing it to land on RWY 23) there’s no evidence of a pilot (either Cdr or FO) mistake. A xwind of 25KTS would be still below the demostrated maximum xwind of the A320 (33KTS gusting 38KTS) even if the gusts would be well above it (although it must be remembered that the demostrated maximum xwind is not a limitation but just the maximum component experienced during aircraft testing).

Diverting to the alternate was an option but, as just said, weather condition could have been suitable for a safe landing considering also that the Emma storm on Central Europe most probably affected all the diverting airfields.

What is less clear is why the pilot did not decide to land on the other RWY available in HAM. In fact, using RWY 33, he would have faced a xwind component with angled by 40° instead of 60°. Using RWY 33, the 28G48KT wind would have meant a xwind component of “only” 18G32KTS with a forecated 24G36KTS. Assuming for example an actual wind of 40Kts from 290° during the approach, the xwind component would have been 35kts on RWY 23 and 26kts on RWY 33: a huge difference even for an experienced pilot.

Furthermore, RWY 33 is longer than 23 (3.666mt vs 3.250 mt) and is equipped with an ILS (Instrumental Landing System) and it’s a pilot responsibility to land on either runway, not an ATC one.

Dealing with the approach, it looked more or less stable until the very short final (not different from many others you can see by clicking here), around 60ft or so. According to the common procedure used with xwind components, the aircraft is correctly crabbed (meaning that it has applied a WCA, Wind Correction Angle, aligning nose and tail with the wind direction while the aircraft is following a different course). Just before touchdown, the pilot tries to reduce the WCA angle in order to prevent landing gear damage; however the “decrab” is extremely important on dry runways, because of the side load that could stress the gear on the gear, while it is not that important on wet runways like Hamburg one on Mar. 1 video.

It seems like the gust that moved the A320 outside the runway acted when the aircraft had been “decrabbed” and aligned with the runway. That is the phase of the landing with xwind in which the airplane is most vulnerable to the gustings and for this reasons, all aircraft (from the little C-152 to the MD-11 with some differences) have to apply cross-controls: left rudder, right aileron (if wind is coming from starboard) meaning rudder and aileron in opposite directions. This doesn’t mean that the aircraft has always to lower the wing on the upwind side (like I did with the Cessna), but this may be required to keep the aircraft on the runway even though many experienced pilots landing on dry runway are able to land with levelled wings.

So, one of the hypothesis, is that the pilot flying the aircraft did not apply cross-controls before touchdown or did apply the corrective input too late (or too slowly).

In order to understand the crabbing and decrabbing procedure, I suggest watching this interesting video:

The recovery was instead perfect. Since the engines need some seconds to spool up from Idle (from 3 to 5 I think) the crew must have started the go around as soon as the aircraft rolled dangerously to port, then the pilot maintained a low pitch and a smooth rate of climb in order to gain speed before trying another approach.

A lightning strike causes the loss of an Italian F-16. Are lightnings a risk for aviation safety?

On Feb. 11, an F-16 of the 37° Stormo of the Italian Air Force, crashed into the sea between Levanzo and Marettimo, not far from Trapani Birgi airbase.

The aircraft had been involved in a night training sortie and was returning to the base when, around 20.00LT, it was struck by a lightning while crossing bad weather.

Maj. Maurizio De Angelis of the 18th Gruppo successfully ejected from the aircraft and was located and rescued from the sea by the crew of a HH-3F helicopter of the Trapani-based 82° Centro SAR.

The aircraft lost is the 5th Italian F-16 crashed since this type of fighter entered service with the ItAF as part of the Peace Cesar program. All the mishaps involved aircraft belonging to the Stormo based in Trapani. The aircraft, whose leasing is going to expire on Dec. 31 2010, should have flown about 27.000 hours (22.250 were logged at May 2007), the 60% of the flight hours bought by the ItAF (45.000 fh) but have a worrying crash rate: something around 1.85 losses for 10.000 flight hours, higher than the AMX (still grounded) and Tornado (grounded for a short period after the last accident).

It must be considered though, that 2 F-16 (MM7246 and MM7263) were lost because of a collision and 1 for a birdstrike in landing (MM7258); the very first one (MM7237) suffered a main generator failure during a night mission and the EPU failed to provide power needed to keep the electrical and hydraulic systems alive.

This is not the first time a military aircraft is lost because of a lightning.

Dealing with the F-16 fleet in the World, in the ’80s there were some cases of aircraft lost after being hit by a lightning strike.

In one of them, it was not the lightning itself to cause the crash but its side effect: it ignited the vapors in the empty tank beneath the fuselage that consequently exploded damaging the hydraulic system.

Someone may wonder if an aircraft is so vulnerable to a lightning strike. The answer is “theoretically not”, because the probability to be hit by a lightning is extremely low (there’s about 1 case each year).

Furthermore, the aircraft, just like a car, is shielded by the so-called Faraday Cage, a sort of cage (hence the name) externally made by a conducting material, that blocks out external static electrical fields: charges redistribute on the conduting material and don’t affect the cage’s interior.

Large commercial planes are larger Faraday Cages: if hit by a lightning when flying next or through a storm (rare, since pilots use the on-board weather radar to avoid CBs and storms that could lead to a hit), they let the current pass through the fuselage until ground, preserving the systems’ integrity.

Commercial aircraft have to satisfy stringent requirements to meet the airwothiness certifications required in the U.S. or Europe. Among them there are also standards for protection against the direct and indirect effects of a lightning strike. In particular, planes must be able to withstand the hit without suffering significant surface damage, without any possibility of accidental fuel ignition in the tanks and preserving the avionics and systems failures induced by the electromagnetic field created by the electrical charges of the lightning.

Have a look at this extremely interesting video (a few others are available on youtube) showing a Qantas 767 flying next to a storm hit by a lightning strike: