Altitude correction for aircraft under non-isa temperature conditions

A new and useful apparatus for automatically correcting for the actual altitude of an aircraft, under non-ISA temperature conditions is provided. An apparatus according to the present invention can be particularly useful in automatically providing altitude correction output to a navigation and control system for an aircraft at selected points along an aircraft flight path where terrain clearance under non-ISA temperature conditions is an important operational parameter. An altitude correction device according to the invention is configured to provide altitude correction output with respect to a predetermined landing site as a function of the following formula to compute the aircraft's relation to the computed path relative to the predetermined landing site: ##EQU1## Where PA1 grad=0.00198 deg/ft PA1 t.sub.o =Taer+grad*Haer PA2 (Taer being the temperature at the landing site and Haer being the landing site elevation) PA1 Tm.act'=273+t.sub.o-0.5*grad*Hind PA1 Tm.std'=288-0.5*grad*Hind Additionally, an altitude correction device according to the present invention is further configured to provide altitude correction output with respect to a predetermined landing site as a function of the following calculation to correct altitude targets: ##EQU2## Where PA1 grad=0.00198 deg/ft PA1 t.sub.o =Taer+grad*Haer PA2 (Taer being the temperature at the landing site and Haer being the landing site elevation) PA1 Tm.act=273+to-0.5*grad*Hact PA1 Tm.std=288-0.5*grad*Hact