Based on what exactly?
Metar for KQSA, a bit of a guess at the load mass (70 to 80 tonnes) with a full fuel load and Boeings 747-400 operating procedures.
Then assuming that 1200' is the altitude agl the aircraft reached plus a stop watch.
So a fair few assumptions then...
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KQSA 291155Z COR 33008G17KT 9999 -TSRA SCT050CB BKN090 BKN170 13/04 A2990 RMK CB OHD MOV N SLP139 WND DATA ESTMD ALSTG/SLP ESTMD 60000 70000 51014=
KQSA 291059Z 35011G17KT 9999 FEW050 BKN065 BKN090 14/05 A2993 RMK WND DATA ESTMD ALSTG/SLP ESTMD=
KQSA 291058Z 35011G17KT 9999 FEW050 BKN080CB BKN150 14/05 A2993 RMK LTG DSNT NW SLP124 WND DATA ESTMD ALSTG/SLP ESTMD=
KQSA 291055Z 02007KT 9999 FEW040 BKN080CB BKN150 18/06 A2994 RMK PK WND 06026/1005 WSHFT 1027 LTG DSNT NW CB DSNT NW SLP124 WND DATA ESTMD ALSTG/SLP ESTMD=