As usual when I have family flying I tend to track the flight.
1. I know ADSB can be unreliable at low altitude
2. I do not know what a normal takeoff profile is for an A330
3. Weather conditions?
4. Curvature of the earth
However:
Here is the cause of my concern:
Mon 02:35:00 PM 51.4647 -0.5095 270° West 162 186 1,500 Level FlightAware ADS-B (LHR / EGLL)
Mon 02:35:27 PM 51.4643 -0.5395 270° West 131 151 2,900 2,571 Climbing FlightAware ADS-B (LHR / EGLL)
Mon 02:35:42 PM 51.4640 -0.5544 269° West 131 151 3,300 1,000 Climbing FlightAware ADS-B (LHR / EGLL)
Mon 02:35:57 PM 51.4638 -0.5696 270° West 142 163 3,400 400 Climbing FlightAware ADS-B (CBG / EGSC)
Mon 02:36:12 PM 51.4635 -0.5852 269° West 157 181 3,500 600 Climbing FlightAware ADS-B (ETR / EGTR)
Mon 02:36:27 PM 51.4631 -0.6037 269° West 170 196 3,700 600 Climbing FlightAware ADS-B (LCY / EGLC)
Mon 02:36:42 PM 51.4626 -0.6239 267° West 185 213 3,800 769 Climbing FlightAware ADS-B (EGLW)
Mon 02:37:06 PM 51.4587 -0.6564 262° West 207 238 4,200 1,395 Climbing FlightAware ADS-B (LHR / EGLL)
Mon 02:37:25 PM 51.4568 -0.6895 268° West 220 253 4,800 1,737 Climbing FlightAware ADS-B (FAB / EGLF)
That seems to me like a very steep climb to 3500' with an equally large drop in corresponding airspeed/VSI. (162 down to 131)
I was also monitoring FR24 and the speeds and altitude were similar.
Please tell me it's not the way it looks??