Quoting Pihero (Reply 149): Yes, the maths for the average speed between these two *radar blips* is fine... |
333kts is a simple approximation, using the law of cosines to correct for the 16 degrees between the two radials, we would get an average speed of 351kts.
Quoting Pihero (Reply 149): To me, if these radar blips were to be credible, they should have shown a continuous track... |
If the a/c had been flying high, the track would be continuous because the a/c
RCS is very large for a modern military radar. However, by assuming a climb profile all the way, the radar returns not only confirm that assumption but also give us a strong indication as to what the a/c must have been doing in order to produce the published observables.
When I built the original scenario in thread 43 without knowing the average speed, I proposed
- 36nm from the radar, returns are strong and consistent. The plane must be flying at 1,000ft or higher
- 67nm out. returns weaken and disappear 97nm out. Therefore the plane must be flying around 5,000ft at that point.
- 167nm out, the aircraft reappears because it is climbing through 18,000ft
- 220nm, radar contact is lost as would be expected with the aircraft around 32,000ft
Then in post 178 of thread 44, I added:
Looking at the data further, I suggest that the suddenly weakening radar returns on radial 295 between approx. 36 and 67 nm out are due to the fact that the low rate of climb of MH370 at that point roughly matched the rate of increase of the minimum target altitude for the radar to detect it. Essentially the target was teetering on the edge of visibility for its altitude. I estimate its rate of climb to be around 125ft/nm. I know, every pilot speaks about ft/min but I do not want to guess the speed at that point. Let's just say that if its ground speed had been 300kts, the rate of climb should have been around 650ft/min.
Clearly, that rate of climb could not have been maintained the whole time because:
- the airplane once out of radar visibility would not have reappeared later because it was not climbing fast enough
- the airplane could not have reached 32,000ft 200 miles out.
I therefore estimate that at about 12,000ft, about 142nm from Penang on the radial 295, the rate of climb was probably doubled to about 250ft/nm (maybe in the range of 1,200 to 1,400 ft/min).
Can a 777 climb at those rates at those altitudes? what are the max climb rates with 40t of fuel on-board at that time? I do not know. My guess is that at low altitudes it should easily climb at better than 2,500ft/min