A Complete Manual for Conducting International Flight Operations

MEL, ER Operations, and Class II Nav

MEL / ER Operations / Class II Nav

Aircraft that are currently operating under a manufacturer's MEL are permitted to fly with inoperative equipment for a limited period of time. The Manufacturer's MEL will specify the time interval at which the inoperative equipment must be repaired in order for the aircraft to be considered airworthy. Standard repair intervals are: A items- the repair interval is specified by the manufacturer; B Items which have a repair interval of 3 days or 72 hours; C Items which allow 10 days or 240 hours; and D Items which have a repair interval of 120 days or 2880 hours.

Aircraft Discrepancies

When deferring inoperative equipment or operating aircraft with inoperative equipment, it is critical for the flight crew to determine if any operational restrictions exist. A very simple example would be a navigation light. The operational restriction would permit flight during the day, but would restrict operations at night. ER Operations, or Extended Range Operations, represent a flight regime where it may be necessary to have multiple back-up systems due to the lack of alternate airports or ground based navigation or ATC facilities,etc.

ER Operations & Restrictions

 Gulfstream type aircraft ER operations are defined as the following:

At this point pilots may be asking themselves what constitutes ER Operations? If the MEL lists an ER restriction, would it be legal to have the equipment deferred on a flight from the West Coast of the U.S. to Hawaii? What about the West Coast of the U.S. to New Zealand? Flight crewmembers should review their individual MEL definitions to determine how the manufacturer interprets ER Operations.


The majority of aircraft operators will not have ETOPS approval due to the burdensome approval process and operational procedures, so it is simply a matter of ensuring that the aircraft is capable of reaching a suitable aerodrome within 180 minutes, single-engine in calm wind. Examples of items which are restricted for ER Operations would be HP Bleed systems, bleed air warning systems, APU systems, etc.


Although it is not clearly defined in the MEL definitions, there is a separate area of MEL restrictions which would apply to aircraft which are conducting extended over-water flight operations. The Federal Aviation Regulations defines extended over-water as: “With respect to aircraft other than helicopters, an operation over water at a horizontal distance of more than 50 nautical miles from the nearest shoreline.” (FAR 1)These types of restrictions would obviously apply to an aircraft departing from the West Coast of the United States to Hawaii. Attached is an example of a MEL item which has extended over-water restrictions.


Other examples of items restricted under extended overwater operations would be ELT’s, overwater equipment, long range navigation systems (IRS, GPS), etc.


Revision date: July 29, 2015

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