Most aircraft approaching the airport are at a significantly higher speed but slowed to within a few knots of the INM designated final approach speed as they came within 2 nautical miles of the runway. There are many other factors associated with departures which contribute to considerably more variation in observed operations. There are procedural differences in the way the departures are performed by various airlines. In addition. there are performance- limiting factors such an aircraft weight, pressure altitude, temperature, and wind which introduce additional sources of variation. Accordingly, a more detailed analysis of departures was performed.
All airlines specify their own standard departure procedures for their flight operations manuals.
These procedures are usually fashioned After the FAA suggested noise abatement departure profile. The profiles of most airlines resemble each other for aircraft with high bypass ratio engines. For low bypass ratio engines, however, the FAA procedure specifies a greater thrust reduction after takeoff than some airlines use. This would result in a steeper climb angle than under the FAA procedure, with all other factors hold equal. The INM data base, on the other hand, has a set of completely defined profiles for each aircraft type which were constricted under the assumption that the FAA procedure is being followed by all aircraft.