Nice work on posting the graphic in mh370-radar.study.pdf

Obviously the assumed groundspeeds in GAP-1, 2 and 3 are wrong (Not due to the person posting the graphic). A Boeing 777 is not capable of groundspeeds of 580 to 588 knots with only a 15 knot tailwind. The maximum groundspeed for the given conditions would be 540 knots. Based on Mach 0.87 (87% of the speed of sound), FL300 (30,000 feet), ISA+11 (temperature is 11 degrees Celsius above standard) and tailwind 15 knots.

I am aware that the primary radar accuracy is degraded in height detection due to refraction. Hence, two different primary radars have different height returns in SEG-3 and 4.

But, what would cause this GAP groundspeed error?

Is there a problem with the radar plotter?

If we ignore the GAP segments, and total the primary radar segments, SEG-1, 2, 3 and 4, the total is 128.2 nautical miles in 908 seconds.

Average groundspeed for primary radar segments is then 508 knots.

Average True airspeed is 493 knots. (508 subtract 15)

Or Mach 0.84 for FL360 (36000 feet) in ISA +11.

Mach 0.84 is a standard divert speed for a Boeing 777.

FL360 (36000 feet) is a standard cruise altitude for flying west.