MH370 Flaperon & Lanseria Pitot Freeze

mh370flaperon
Flaperon being tested by CSIRO to determine effect of wind and current.  ©CSIRO 

Malaysian Airlines has become the first operator to monitor all its planes using satellites which will track aircraft in real time – this after its MH370 flight with 239 souls on board disappeared in 2014 during a flight from Kuala Lumpur to Beijing.   The mystery of the flight continues to fascinate and horrify aviators with so many of the basic questions unanswered.   Who took control of the flight?  Why?  Where did the plane disappear?  What happened to the passengers and crew?   How did an entire airliner vanish?

After some criticism about the manner of the search,  Malaysian Airlines has now agreed to sign up for the live monitoring of its planes in a new system which exploits satellite and GPS technology.  This is a long overdue decision and the Malaysians must be congratulated in being the first to move its monitoring to a real-time approach.

MH370Flaperon2
CSIRO staff floating the flaperon

There is also good news when it comes to the search itself.  We may be a little closer to the answers after the Australian Transport Board published its latest report into the search on Friday 21st April.   From the report:

The only thing that our recent work changes is our confidence in the accuracy of the estimated location, which is within the new search area identified and recommended by the First Principles Review (ATSB2016), and most likely at the southern end of that, near 35°S.

While at first glance this appears to merely confirm previous analysis,  there’re quite a few interesting items in the CSIRO (Commonwealth Scientific and Industrial Research Organisation )Oceans and Atmosphere report which was handed to authorities on the 13th April and released publicly today.   Earlier attempts at computer generated modelling were linked to the manner in which buoys floated in the ocean,  and not how a flaperon would react to currents and winds.   This report has painstakingly pulled this specific data into a model which scientists at the CSIRO and ATB believe has allowed for a much more accurate rendering of the location of the fuselage.

MH370Northsearch
The Red indicates the area where CSIRO now believes is the zone which contains the remains of MH370

That’s because the Flaperon reacts like a sail in wind,  and more so because part of the same wing structure would also glide through the water like a boat.  Combine these two aspects and it makes for very interesting data.  The tests found that the Flaperon would move 20° left of the wind at an average of 10cm/s and would account for the Flaperon’s  arrival time of the flaperon at La Reunion in July 2015.  So the report states:

The value of this revised estimate of the flaperon’s drift parameters is that it increases our confidence in the accuracy of the drift model. The earlier simulations of the flaperon trajectory were only consistent with the arrival of the flaperon at La Reunion if a chance encounter with an ocean eddy took the flaperon south. That was plausible but not particularly likely.

While the scientists warn that that doesn’t automatically mean that the debris would DEFINITELY arrive at La Reunion,  they’re now confident about the site of the crash itself.  It’s still a vast area 25000km/squared.   Importantly,  they also now know precisely where the plane WOULDN’T be based on the same modelling.  It’s a bit like the ancient Arab mathematicians discovering that 0 is very important.  Nothing is as important as something sometimes.

MH370flow
The data map of possible wreckage flow based on CSIRO computer modelling 

“Nothing” was what my airspeed indicator read half way along a ground roll at Lanseria last week which was a real surprise.  After all the checks (double checks in my case because I’m extra cautious), power run up and physical inspection,  I still had a frozen pitot tube problem on ground roll.   One moment power is 2500 RPM and airspeed is coming up nicely,  past 23-30knots then suddenly – ZERO!

Nadah

Nix

The SR20 had accelerated quickly at first and felt good but my airspeed indicator then read “——”   indicating  I had stopped when it was clear we were approaching V1 speed along Runway 07 at Lanseria.

The years of training kicked in,  power back, brakes on, off at Alpha 1 and report to ATC that my flight was aborted due to technical problems.  He asked as per the book if I needed assistance and I said no,  trouble with airspeed and returned to the hangar.

IMG_2279
The dew that was to cause the problem.  I took the picture to show the extend of the dew fall on the morning of 16th April 2017.  

After shutting down I looked into the tube but saw nothing.   An instructor Michelle Roe arrived and turned on the pitot tube heat.  After five minutes steam began to blow out of the tube and it was as right as rain but I had missed the window for my flight.

pitotTube
A typical light aircraft Pitot Tube

While the end of this story is positive,  I sat there thinking about the Air France Flight 447 in 2009 that crashed because its pitot tube that was frozen, leading the pilots to take the instrument reading as correct when the real story was the plane was falling in a flat stall straight down into the Atlantic.   In my case it was daylight and I knew immediately what the problem was because after seeing the computer flight display indicate zero on speed,  I looked at the backup analogue old fashioned airspeed indicator which also read zero.  At that point I knew that the pitot tube was blocked.  But had it been at night and at 5000 AGL there would have been problems.

pitot_tubejet
Pitot Tube on an airliner of jet would look something like this.

If it had been at night,  the only solution here would be at first try the pitot tube heat while changing to autopilot,  then if the airspeed failed to reappear,  to pull the CAPs lever or Cirrus parachute system.  The water in the pitot tube had actually frozen on a sunny day while on the ground and accelerating – I could only imagine how difficult it was for the Air France pilots.  In my case the temperature at the time was 12˙C and the dew fall had been extremely heavy in the morning.  The water was dripping off the plane as I did the checks and I noted at the time (see the picture above!) that the pitot tube cover had not been used on the Cirrus overnight,  even though it was parked outdoors.

Usually the thing that concerns me most is the worry that an insect had crawled into the tube.  But a visual inspection indicated the tube was not blocked by a wasp or similar.  I just didn’t see how much water had flowed into the tube,  and during the ground roll more water must have entered the tube leading to the block.

The design of the pitot tube goes back a hundred years or more with the basic principle a comparison of air pressure inside a controlled machine vs the changing air pressure outside.  That produced a number of things,  airspeed,  rate of climb or descent,  and altitude.   So had I decided to ignore the zero reading on the pitot tube and taken off,  my flight would have probably entailed a violent altercation with the granite cloud.

An accident.

Instead because we’re trained properly,    CCT was flying an hour later quite safely.

Unlike Air France Flight 447.

Physics_pitot
The physics of a Pitot Tube courtesy of NASA 

 

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