En Route Safety Considerations

In order to increase fuel state awareness, pilots are required to monitor the time and fuel remaining during an IFR flight. For example, on a flight scheduled for one hour or less, the flight crew may record the time and fuel remaining at the top of climb (TOC) and at one additional waypoint listed in the flight plan. Generally, TOC is used in aircraft with an FMS, and represents the point at which cruise altitude is first reached. TOC is calculated based on current altitude, climb speed, and cruise altitude. The pilot may elect to delete the additional waypoint recording requirement if the flight is so short that the record will not assist in the management of the flight. For flights scheduled for more than one hour, the pilot may record the time and fuel remaining shortly after TOC and at selected waypoints listed in the flight plan, conveniently spaced approximately one hour apart. The actual fuel burn is then compared to the planned fuel burn. Each fuel tank must be monitored to verify proper burn off and appropriate fuel remaining. For two-pilot aircraft, the pilot monitoring (PM) keeps the flight plan record. On three-pilot aircraft, the second officer and PM coordinate recording and keeping the flight plan record. In all cases, the crew member(s) making the recording communicates the information to the pilot flying.

OpSpecs for commercial operators include provisions for en route emergency diversion airport requirements. Operators are expected to develop a sufficient set of emergency diversion airports, so that one or more can be reasonably expected to be available in varying weather conditions. The flight must be able to make a safe landing, and the airplane maneuvered off of the runway at the selected diversion airport. In the event of a disabled airplane following landing, the capability to move the disabled airplane must exist so as not to block the operation of any recovery aircraft. In addition, those airports designated for use must be capable of protecting the safety of all personnel by being able to:

Part 91 operators also need to be prepared for a diversion. Designation of an alternate on the IFR flight plan is a good first step; but changing weather conditions or equipment issues may require pilots to consider other options.