Yep —
According to the Malaysian military thus far, after taking 2 minutes to turn around, the plane went up to 45,000ft and flew at the new western heading for 23 minutes — but how fast they didn’t say. Apparently they are saying now and it was faster than thought.
Then after those 23 minutes it dropped down to 12,000ft and as low as 5,000 — but how fast it was flying and for how long at that altitude Malaysia would not say. Apparently they are saying now and it was faster and longer than thought.
If it then flew faster at 12,000ft it would have not only used up more fuel but also have gone further toward waypoint IGREX than their 450 model was assuming.
Note that on that graph the 400 red line south begins up further northwest than the 450. The 450 yellow line also shows a flight path over Indonesia which I don’t think this pilot would risk.
The faster it went for the first 2, hours, the slower it had to go for the last 5 hours to hit those Inmarsat pings rings.
Hence the 400 knot route and the new search area. They should have been in that area 3 weeks ago.
Here’s another way to look at it, assuming they knew the original fuel load:
They could calculate the fuel usage given the know route and altitude for the time until it left radar range. Deducting that from the original fuel would give the fuel remaining.
Now, they know the approximate time the plane was in the air with that remaining fuel load. From that, they should have been able to deduce the plane’s average airspeed over the remaining time, knowing the fuel usage statistics of the engines involved.
For example, if you’ve got 20 gallons of gas in your car and run out of gas in five hours, you then used 4 gallons per hour. If driving at 60 gives you 15 mpg, and at 72 gives you 12 mpg, you know you averaged 60 mph because you were using 4 gallons per hour over five hours. If you’d have averaged 72 mph, you’d have used 6 gallons per hour and run out of gas in 3 hours and 20 minutes, but the 5 hours is a given so you couldn’t have gone 72 mph.
So knowing the fuel remaining and the time in the air would allow calculation of an average airspeed, just as driving 5 hours on 20 gallons would imply an average speed of 60 mph given the characteristics of the car engine involved.
For what it’s worth, I still this this is a crap shoot because if the pilot was still in control he could have varied the altitude which would blow the calculation. It would be similar to being on a 5 hour downhill grade in the car example. You’d get a lot better mileage.