The airlines cannot modify aircraft. Any aircraft modification has to be designed and tested by the aircraft manufacturer and then approved by a regulator. Most of the times an approval from FAA and EASA on the modification is accepted by most countries.
When it comes to high altitude operations there are two main factors that comes into play. They are:
- Engine thrust requirements: At higher altitudes, the reduced air density means, the engines produce less thrust. So, generally a higher amount of thrust is required to take off from a high altitude airport.
- Passenger Oxygen requirements: Higher altitude airports means that the automatic passenger Oxygen mask drop altitude has to be changed. There is also need for extra Oxygen carrying capability. For example, the Chinese CAAC requires an operator to carry 55 minutes of Oxygen if the aircraft is operated at high terrain and high altitude airports. Normally, it is 15 minutes.
There are airplanes which have later been modified for high altitude operations. One example is the Airbus A319. Under EASA type certificate modification number, SC E-10, the aircraft is given the ability to operate from airports as high as 14100 ft. This is about a 5000 ft higher altitude than what it was initially certified for. Some of the modifications applied to the aircraft is the addition of a thrust bump. The thrust bump gives an about a 10% increase in TOGA thrust for take off. The thrust bump is activated by pressing two red push buttons which are placed on the back of the thrust levers.
The other interesting modification is the addition of a high altitude landing switch on the overhead panel. When turned on, the passengers Oxygen masks are armed to drop if the cabin altitude exceeds 16000 ft. Normally, in A320 family aircraft, they are armed at 14000 ft. This allows the aircraft to operate in an out of aerodromes which are at 14000 ft altitude without the risk of dropping of passenger Oxygen.
Author – Anas Maaz ( Airline Pilot )
