Altitude simulation ignition tests of a single spool small turbojet starting were completed at an altitude test rig.Some conclusions from the test data analysis have been drawn.It is very useful to supply secondary oxygen jet for high altitude ignition and starting.The use of high energy igniter improves ignition and starting performance and reduces starting time.Fuel flow must be matched with air flow during the high altitude starting.The fuel flow must be controlled by the rotational velocity of the rotor to limit temperaturet 4 and to avoid hang up during the starting.