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.
    3. Contingency procedures applicable only to the New York Oceanic CTA/FIR are detailed below in Paragraph 6, New York Contingency Procedures Including Turn-Backs.
  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.
  6. New York Contingency Procedures Including Turnbacks
    1. Introduction
      1. The procedures contained herein for operations in the New York Center Oceanic CTA/FIR are to be used in place of the procedures contained in ENR 7.3, paragraphs 2 and 4.
      2. Although all possible contingencies cannot be covered, the procedures in paragraphs 6.2, 6.3, and 6.4 provide for the more frequent cases, such as:
        1. Inability to comply with assigned clearance due to meteorological conditions (see paragraph 6.4);
        2. En route diversion across the prevailing traffic flow (for example, due to medical emergencies (see paragraphs 6.2 and 6.3); and
        3. A loss, or significant reduction of, the required navigation capability when operating in airspace where the navigation performance accuracy is a prerequisite to the safe conduct of flight operations; or in the event of pressurization failure (see paragraphs 6.2 and 6.3)

          NOTE-

          Guidance on procedures to follow when an aircraft experiences a degradation in navigation capabilities can be found in ICAO Doc 4444, Procedures for Air Navigation Services – Air Traffic Management, Chapter 5, section 5.2.2.

      3. The pilot shall take action as necessary to ensure the safety of the aircraft. The pilot's judgement shall determine the sequence of actions to be taken in regard to the prevailing circumstances. Air traffic control shall render all possible assistance.
    2. General Procedures

      NOTE-

      Figure ENR 7.3-1 provides an aid for understanding and applying the contingency procedures contained in paragraphs 6.2 and 6.3.

      1. If an aircraft is unable to continue the flight in accordance with its ATC clearance, a revised clearance shall be obtained, whenever possible, prior to initiating any action.
      2. If prior clearance cannot be obtained, the following contingency procedures should be employed until a revised clearance is received:
        1. Leave the cleared route or track by initially turning at least 30 degrees to the right or to the left in order to intercept and maintain a parallel, same direction track or route offset 9.3 km (5.0 NM). The direction of the turn should be based on one or more of the following:
          1. Aircraft position relative to any organized track or route system;
          2. The direction of flights and flight levels allocated on adjacent tracks;
          3. The direction to an alternate airport;
          4. Any strategic lateral offset being flown; and
          5. Terrain clearance;
        2. The aircraft should be flown at a flight level and an offset track where other aircraft are less likely to be encountered;
        3. Watch for conflicting traffic both visually and by ACAS (if equipped), leaving ACAS in RA mode at all times unless aircraft operating limits dictate otherwise;
        4. Turn on all aircraft exterior lights (commensurate with appropriate operating limitations);
        5. Keep the SSR transponder on at all times and, when able, squawk 7700, as appropriate;
        6. As soon as practicable, the pilot shall advise air traffic control of any deviation from assigned clearance;
        7. Use whatever means is appropriate (i.e., voice and/or CPDLC) to communicate during a contingency or emergency;
        8. If voice communication is used, the radiotelephony distress signal (MAYDAY) or urgency signal (PAN PAN), preferably spoken three times, shall be used as appropriate;
        9. When emergency situations are communicated via CPDLC, the controller may respond via CPDLC. However, the controller may also attempt to make voice communication contact with the aircraft;

          NOTE-

          Additional guidance on emergency procedures for controllers, radio operators, and flight crew, in data link operations can be found in the Global Operational Data Link (GOLD) Manual (Doc10037).

        10. Establish communications with 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). Also broadcast where appropriate on the frequency in use: aircraft identification, the nature of the distress condition, intention of the person in command, position (including the ATS route designator or the track code, as appropriate), and flight level; and
        11. The controller should attempt to determine the nature of the emergency and ascertain any assistance that may be required. Subsequent ATC action with respect to that aircraft must be based on the intentions of the pilot and overall traffic situation.
    3. Actions to be Taken Once Offset from Track

      NOTE-

      The pilot's judgement of the situation and the need to ensure the safety of the aircraft will determine whether the actions outlined in 6.3.2.1 or 6.3.2.2 will be taken. Factors for the pilot to consider when diverting from the cleared route or track without an ATC clearance include, but are not limited to: operation within a parallel track system; the potential for User Preferred Routes (UPR) parallel to the aircraft's track or route; the nature of the contingency (for example, aircraft system malfunction); and weather factors (for example, convective weather at lower flight levels).

      1. If possible, maintain the assigned flight level until established on the 9.3 km (5.0 NM) parallel, same direction track or route offset. If unable, initially minimize the rate of descent to the extent that is operationally feasible.
      2. Once established on a parallel, same direction track or route offset by 9.3 km (5.0 NM), either:
        1. Descend below FL 290, establish a 150 m (500 ft) vertical offset from those flight levels normally used, and proceed as required by the operational situation or, if an ATC clearance has been obtained, proceed in accordance with the clearance, or

          NOTE-

          Descent below FL 290 is considered particularly applicable to operations where there is a predominant traffic flow (for example, east-west) or parallel track system where the aircraft's diversion path will likely cross adjacent tracks or routes. A descent below FL 290 can decrease the likelihood of conflict with other aircraft, ACAS RA events, and delays in obtaining a revised ATC clearance.

        2. Establish a 150 m (500 ft) vertical offset (or 300 m (1000 ft) vertical offset if above FL 410) from those flight levels normally used, and proceed as required by the operational situation, or if an ATC clearance has been obtained, proceed in accordance with the clearance.

          NOTE-

          Altimetry system error may lead to less than actual 150 m (500 ft) vertical separation when the procedure above is applied. In addition, with the 150 m (500 ft) vertical offset applied, ACAS RAs may occur.

          FIG ENR 7.3-1
          Visual Aid for Understanding and Applying the Contingency Procedures Guidance

          A graphic depicting the special procedures for in-flight contingencies in oceanic airspace (nonw eather).
    4. Weather Deviation Procedures
      1. General

        NOTE-

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

        1. When weather deviation is required, the pilot should contact ATC via CPDLC or voice. A rapid response may be obtained by either:
          1. Stating, “WEATHER DEVIATION REQUIRED” to indicate that priority is desired on the frequency and for ATC response; or
          2. Requesting a weather deviation using a CPDLC lateral downlink message.
        2. When necessary, the pilot should initiate the communications using the urgency call “PAN PAN” (preferably spoken three times) or by using a CPDLC urgency downlink message.
        3. The pilot shall inform ATC when a weather deviation is no longer required, or when a weather deviation has been completed and the aircraft has returned to its cleared route.
      2. Actions to be Taken When Controller-Pilot Communications Are Established
        1. The pilot should notify ATC and request clearance to deviate from track or route, advising when possible the extent of the deviation requested. The flight crew will use whatever means are appropriate (i.e., CPDLC and/or voice) to communicate during a weather deviation.

          NOTE-

          Pilots are advised to contact ATC as soon as possible with requests for clearance in order to provide time for the request to be assessed and acted upon.

        2. 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 should:
            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.
        3. 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 provided in paragraph 6.4.3.
      3. Actions to be Taken if a Revised ATC Clearance Cannot Be Obtained:

        NOTE-

        The provisions of this paragraph 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 or route to avoid adverse meteorological conditions, and prior clearance cannot be obtained, an ATC clearance shall be obtained at the earliest possible time. Until an ATC clearance is received, the pilot shall 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;
          4. Turn on all aircraft exterior lights (commensurate with appropriate operating limitations);
          5. For deviations less than 9.3 km (5.0 NM) from the originally cleared track or route, remain at a level assigned by ATC;
          6. For deviations greater than or equal to 9.3 km (5.0 NM) from the originally cleared track or route, when the aircraft is approximately 9.3 km (5.0 NM) from track, initiate a level change in accordance with TBL ENR 7.3-2.
          7. If the pilot receives clearance to deviate from the cleared track or route for a specified distance and subsequently requests but is denied clearance to deviate beyond that distance, the pilot should apply an altitude offset in accordance with TBL ENR 7.3-2 immediately;
          8. When returning to track or route, be at the assigned flight level when the aircraft is within approximately 9.3 km (5.0 NM) of the centerline.
        2. 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.

          NOTE-

          If, as a result of actions taken under the provisions of 6.4.3.1 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.

TBL ENR 7.3-2
Altitude Offset When Denied Clearance to Deviate 9.3 km (5.0 NM) or More

Originally Cleared Track or
Route Center Line

Deviations
> 9.3 km (5 NM)

Level Change

EAST
(000° - 179° magnetic)

LEFT

DESCEND
90 m (300 ft)

RIGHT

CLIMB
90 m (300 ft)

WEST
(180° - 359° magnetic)

LEFT

CLIMB
90 m (300 ft)

RIGHT

DESCEND
90 m (300 ft)