ENR 7.3 Special Procedures for In-Flight Contingencies in Oceanic Airspace

  1. Introduction
    1. Although all possible contingencies cannot be covered, these procedures provide for the more frequent cases such as:
      1. Inability to comply with assigned clearance due to meteorological conditions, aircraft performance, or pressurization failure;
      2. En route diversion across the prevailing traffic flow; and
      3. Loss of, or significant reduction in, the required navigation capability when operating in airspace where the navigation performance accuracy is a prerequisite to the safe conduct of flight operations.
    2. The procedures are applicable primarily when descent and/or turn back or diversion is required. The pilot must take action as necessary to ensure the safety of the aircraft, and the pilot's judgment must determine the sequence of actions to be taken, having regard to the prevailing circumstances. Air traffic control must render all possible assistance.
  2. General Procedures
    1. If an aircraft is unable to continue the flight in accordance with its ATC clearance, and/or an aircraft is unable to maintain the navigation performance accuracy specified for the airspace, a revised clearance must be obtained, whenever possible, prior to initiating any action.
    2. The radiotelephony distress signal (MAYDAY) or urgency signal (PAN PAN) preferably spoken three times must be used as appropriate. Subsequent ATC action with respect to that aircraft must be based on the intentions of the pilot and the overall air traffic situation.
    3. If prior clearance cannot be obtained, until a revised clearance is received the following contingency procedures should be employed and the pilot must advise air traffic control as soon as practicable, reminding them of the type of aircraft involved and the nature of the problem. In general terms, the aircraft should be flown at a flight level and on an offset track where other aircraft are least likely to be encountered. Specifically, the pilot must:
      1. Leave the assigned route or track by initially turning at least 45 degrees to the right or to the left, in order to acquire a same or opposite direction track offset 15 NM (28 km) from the assigned track centerline. When possible, the direction of the turn should be determined by the position of the aircraft relative to any organized route or track system. Other factors which may affect the direction of the turn are:
        1. The direction to an alternate airport;
        2. Terrain clearance;
        3. Any strategic lateral offset being flown, and:
        4. The flight levels allocated on adjacent routes or tracks;
      2. Having initiated the turn:
        1. If unable to maintain the assigned flight level, initially minimize the rate of descent to the extent that is operationally feasible. Pilots should take into account the possibility that aircraft below on the same track may be flying a 1 or 2 NM strategic lateral offset procedure (SLOP) and select a final altitude which differs from those normally used by 500 ft (150 m) if at or below FL 410, or by 1,000 ft (300 m) if above FL 410; or
        2. If able to maintain the assigned flight level, once the aircraft has deviated 10 NM (19 km) from the assigned track centerline, climb or descend to select a flight level which differs from those normally used by 500 ft (150 m), if at or below FL 410, or by 1,000 ft (300m) if above FL 410.
      3. Establish communications with and alert nearby aircraft by broadcasting, at suitable intervals on 121.5 MHz (or, as a backup, on the inter-pilot air-to-air frequency 123.45 MHz) and where appropriate on the frequency in use: aircraft identification, flight level, position (including the ATS route designator or the track code, as appropriate) and intentions;
      4. Maintain a watch for conflicting traffic both visually and by reference to ACAS (if equipped);
      5. Turn on all aircraft exterior lights (commensurate with appropriate operating limitations); and
      6. Keep the SSR transponder on at all times.
    4. When leaving the assigned track:
      1. If the intention is to acquire a same direction offset track, the pilot should consider limiting the turn to a 45 degree heading change, in order not to overshoot the offset contingency track; or
      2. If the intention is to acquire and maintain an opposite direction offset track, then:
        1. Operational limitations on bank angles at cruising altitudes will normally result in overshooting the track to be acquired. In such cases a continuous turn should be extended beyond 180 degrees heading change, in order to re-intercept the offset contingency track as soon as operationally feasible; and
        2. Furthermore, if executing such a turn back in a 30 NM (56km) lateral separation route structure, extreme caution pertaining to opposite direction traffic on adjacent routes must be exercised and any climb or descent, as specified in 2.3.2.2 above, should be completed preferably before approaching within 10 NM (19km) of any adjacent ATS route.
  3. Extended Range Operations by Airplanes with Two-Turbine Power-Units (ETOPS)
    1. If the contingency procedures are employed by a twin-engine aircraft as a result of an engine shutdown or failure of an ETOPS critical system, the pilot should advise ATC as soon as practicable of the situation, reminding ATC of the type of aircraft involved, and request expeditious handling.
  4. General Weather Deviation Procedures

    NOTE-

    The following procedures are intended for deviations around adverse meteorological conditions.

    1. When the pilot initiates communications with ATC, a rapid response may be obtained by stating “WEATHER DEVIATION REQUIRED" to indicate that priority is desired on the frequency and for ATC response. When necessary, the pilot should initiate the communications using the urgency call “PAN PAN" (preferably spoken three times).
    2. The pilot should notify ATC and request clearance to deviate from track, advising, when possible, the extent of the deviation expected.
    3. ATC should take one of the following actions:
      1. When appropriate separation can be applied, issue clearance to deviate from track; or
      2. If there is conflicting traffic and ATC is unable to establish appropriate separation, ATC must:
        1. Advise the pilot of inability to issue clearance for the requested deviation;
        2. Advise the pilot of conflicting traffic; and
        3. Request the pilot's intentions.
    4. The pilot should take one of the following actions:
      1. Comply with the ATC clearance issued; or
      2. Advise ATC of intentions and execute the procedures detailed in the section below on “Actions to be taken if a revised ATC clearance cannot be obtained."
    5. Actions to be taken if a revised ATC clearance cannot be obtained:

      NOTE-

      These provisions apply to situations where a pilot needs to exercise the authority of a pilot-in-command under the provisions of ICAO Annex 2 ,2.3.1 .

      1. If the aircraft is required to deviate from track to avoid adverse meteorological conditions and prior clearance cannot be obtained, an ATC clearance must be obtained at the earliest possible time. Until an ATC clearance is received, the pilot must take the following actions:
        1. If possible, deviate away from an organized track or route system;
        2. Establish communications with and alert nearby aircraft by broadcasting, at suitable intervals: aircraft identification, flight level, position (including ATS route designator or the track code) and intentions, on the frequency in use and on 121.5 MHz (or, as a backup, on the inter-pilot air-to-air frequency 123.45 MHz);
        3. Watch for conflicting traffic both visually and by reference to ACAS (if equipped);

          NOTE-

          If, as a result of actions taken under the provisions of items 4.5.1.2 and 4.5.1.3 above, the pilot determines that there is another aircraft at or near the same flight level with which a conflict may occur, then the pilot is expected to adjust the path of the aircraft, as necessary, to avoid conflict.

        4. Turn on all aircraft exterior lights (commensurate with appropriate operating limitations);
        5. Deviations of less than 10 NM (19 km) should REMAIN at ASSIGNED altitude. Otherwise, when the aircraft is approximately 10 NM (19 km) from track, initiate an altitude change in accordance with TBL ENR 7.3-1.
        6. When returning to track, be at its assigned flight level when the aircraft is within approximately 10 NM (19 km) of the centerline; and
        7. If contact was not established prior to deviating, continue to attempt to contact ATC to obtain a clearance. If contact was established, continue to keep ATC advised of intentions and obtain essential traffic information.
    6. The pilot must inform ATC when weather deviation is no longer required, or when a weather deviation has been completed and the aircraft has returned to its cleared route.

      TBL ENR 7.3- 1

      Route Centerline Track

      Deviations
      > 10 NM (19 km)

      Altitude Change

      EAST
      (000°- 179° magnetic)

      LEFT


      RIGHT

      DESCEND
      300 ft (90 m)

      CLIMB
      300 ft (90 m)

      WEST
      (180°- 359° magnetic)

      LEFT


      RIGHT

      CLIMB
      300 ft (90 m)

      DESCEND
      300 ft (90 m)

      Pilot Memory Slogan: “East right up, West right down.”

  5. Houston/Miami/New York Oceanic CTA/FIR National Winter Storm Operations
    1. During the winter season, the U.S. Air Force Reserves (AFRES), 53rd Weather Squadron has responsibility for flying winter storm reconnaissance missions. Mission aircraft will fly at altitudes between FL290 and FL350. At designated points, the aircraft will release dropsondes, 16-inch cardboard weather cylinders weighing one pound, each with an attached parachute. When in areas with no direct pilot-controller VHF/UHF communications, at five minutes prior to dropsonde release, the mission aircraft commander will broadcast on 121.5 and 243 the time and position of the intended drop. The dropsonde falls at a rate of approximately 2500 feet per minute.
    2. Aircraft commanders are directly responsible for or the release of any objects from the aircraft. ATC must provide traffic advisories, when feasible, to the aircraft. ATC will provide separation between the mission aircraft and any nonparticipating aircraft. ATC cannot provide separation between aircraft and the dropsonde.
    3. NOTAMs will be issued as early as possible prior to each mission. Airspace operators should consider any national winter storm operations during flight planning in the affected area(s) and nonparticipating aircrews should be especially alert to pertinent broadcasts on 121.5 or 243.0 during national winter storm operations.