FlightAware Discussions

Germanwings crash in France

uk.news.yahoo.com/passenger-pla … ml#xuJ27LO

A Germanwings airliner crashed today flying over the French Alps. There were something like 140 people on board.

It seems like the plane descended very rapidly, even though it wasn’t landing nearby.

Germanwings Lufthansa’s budget , was 50 minutes into its flight with 150 aboard from Barcelona in relatively clear weather when it dropped from a cruising altitude of 38,000 feet to around 6,800 feet over the town of Barcelonnette. The eight-minute descent was [unusually] rapid, but possibly controlled though it left the plane too low to navigate the mountains.

The FlightAware graph for the flight is very interesting:
flightaware.com/live/flight/GWI9 … L/tracklog

All of the data was generated by ADS-B. This means that the data came from the plane’s on board sensors.
The graph is interesting in 2 ways. The first obvious point is that the plane appears to have descended rapidly while maintaining airspeed. This is what is being reported in the media.

I’m not an expert, but in addition to the above, the airspeed line on the graph shows 2 interesting things.

  1. It could be corrupt Flightaware data, but there seems to have been a glitch in the airspeed at about 12 minutes into the flight. This could indicate a problem with the airspeed instrumentation. Note that the same chart on FlightRadar24 does not show the glitch.

  2. About 4 minutes after the plane started to descend, the airspeed on the graph starts to reduce. However the rate of reduction tapers off in a very smooth curve. This part of the chart looks like what you would expect if an airspace was equalizing. Could we be looking at a pitot tube problem?

I welcome any thoughts on this observation. As I said, I am not an expert.

  1. Not sure about the older A320’s but most newer generation jets have the capability for the autopilot to initiate and fly an emergency decent due to a loss of pressurization. Normally they are programed to level off in the 15,000 ft. area. The graph looks like an idle power/red line descent, if the pilots are awake and have done their part of the emergency descent checklist they would normally deploy the speedbrakes which would have given the airplane a much higher rate of descent than shown here, 9,000 fpm or so. In my view either the pilots were content with what amounts to a slightly higher than normal descent rate in a non-emergency situation OR they were not awake.

  2. The groundspeed on the graph is consistent with flying at Mmo/Vmo (red line on the airspeed indicator). For those who don’t know, True airspeed = indicated airspeed corrected for temperature. Groundspeed = true airspeed corrected for winds.

  3. As usual there is lot’s of speculation out there, even the graphs on the internet need to be taken with caution, they are only updated once or twice per minute.

I am not an expert, played flightsimulator a few times.

Is it possible that the aircraft did a descent to pick up ILS from Barcelona airport, but for some reason put in the waypoint for Barcelonnette airport when trying to return to Barcelona?

It’s just running thru my head the whole time because the almost similar names and because it was so close to Barcelonnette. I remember a passenger plane shot down by Russian jet, after they put in a wrong(incomplete) waypoint.

Good thought but not likely.

  1. In that area there are plenty of larger airports the crew would choose if they needed to divert.
  2. The Flight Management computers used today are normally programmed using 3,4 or 5 letter codes for the waypoints. In the case of the Korean flight you mentioned they were inputting actual latitude and longitude navigation points.
  3. For the autopilot to fly an ILS several things have to happen. First the crew enters the 4 letter airport code into the FMS. Second they must select a runway then the ILS for that runway. At this point all of the waypoints associated with the ILS have been entered into the flight plan portion of the FMS. Next the crew enters either a heading to intercept the localizer or selects a waypoint to fly direct to. Finally “ILS” must be selected as an active mode AND a valid signal received and the crew must select an altitude that allows the airplane to leave its cruise altitude.

As a followup to my first post, apparently Airbus has never had an automatic descent mode.

Thanks Porterjet for clearing it up. And sorry for speculating…

You are right, I watched this guy in a simulator performing ILS approach with a320. He had to descent manually to 2200 and adjust speed and flaps just before locking on to the localizer.

I might have mixed up that korean flight with another accident. I remember a case where the pilot typed in the waypoint, then in the next screen of the flightplanner it showed a “duplicate names” list where the pilot chose the wrong waypoint and the plane went off course and something bad happened.

Thanks again.

Under the graphic in the Washington Post, credit is given to FlightAware, but it’s misspelled Flightware.com.

washingtonpost.com/world/how … aphic.html

Also, the pilot was locked out of the cockpit. And couldn’t get anyone to let him back in!

nytimes.com/2015/03/26/world … crash.html