Landing at the Nearest Suitable Airport
“Plan to land at the nearest suitable airport” is a phrase used in the QRH. This
section explains the basis for that statement and how it is applied. In a non-normal situation, the pilot-in-command, having the authority and responsibility for operation and safety of the flight, must make the decision to continue the flight as planned or divert. In an emergency situation, this authority may include necessary deviations from any regulation to meet the emergency. In all cases, the pilot-in-command is expected to take a safe course of action.
The QRH assists flight crews in the decision making process by indicating those situations where “landing at the nearest suitable airport” is required. These situations are described in the Checklist Introduction or the individual NNC.
The regulations regarding an engine failure are specific. Most regulatory agencies specify that the pilot-in-command of a twin engine airplane that has an engine failure or engine shutdown shall land at the nearest suitable airport at which a safe landing can be made.
737 Flight Crew Training Manual
A suitable airport is defined by the operating authority for the operator based on guidance material, but in general must have adequate facilities and meet certain minimum weather and field conditions. If required to divert to the nearest suitable airport (twin engine airplanes with an engine failure), the guidance material also typically specifies that the pilot should select the nearest suitable airport “in point of time” or “in terms of time.” In selecting the nearest suitable airport, the pilot-in-command should consider the suitability of nearby airports in terms of facilities and weather and their proximity to the airplane position. The pilot-in-command may determine, based on the nature of the situation and an examination of the relevant factors, that the safest course of action is to divert to a more distant airport than the nearest airport. For example, there is not necessarily a requirement to spiral down to the airport nearest the airplane's present position if, in the judgment of the pilot-in-command, it would require equal or less time to continue to another nearby airport.
For persistent smoke or a fire which cannot positively be confirmed to be completely extinguished, the safest course of action typically requires the earliest possible descent, landing and evacuation. This may dictate landing at the nearest airport appropriate for the airplane type, rather than at the nearest suitable airport normally used for the route segment where the incident occurs.
Air Systems Cabin Altitude Warning
There have been several reports of cabin altitude warning alerts caused by improperly configured engine bleed air and air conditioning pack switches. This condition is often the result of crews failing to reconfigure switches following a no engine bleed takeoff. Additionally, there have been reports of crews delaying their response to the cabin altitude warning alert because it was confused with the takeoff configuration warning horn.
In order to address the problem of incorrectly positioning switches that affect pressurization, the normal takeoff procedure has been modified to direct the crew to set or verify the correct position of the engine bleed air and air conditioning pack switches after flap retraction is complete. Engine bleeds and air conditioning packs have also been included as specific items in the After Takeoff normal checklist. Additionally, when doing a no engine bleed takeoff, reference to the No Engine Bleed Takeoff supplementary procedure, in conjunction with good crew coordination, reduces the possibility of crew errors.
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FCT 737 (TM) October 31, 2006
737 Flight Crew Training Manual
Confusion between the cabin altitude warning horn and the takeoff configuration warning horn can be resolved if the crew remembers that the takeoff configuration warning horn is only armed when the airplane is on the ground. If this horn is activated in flight, it indicates that the cabin altitude has reached 10,000 feet. In this case, the crew should immediately initiate the Cabin Altitude Warning or Rapid Depressurization NNC.
Ditching Send Distress Signals
Transmit Mayday, current position, course, speed, altitude, situation, intention, time and position of intended touchdown, and type of airplane using existing air-to-ground frequency. Set transponder code 7700 and, if practical, determine the course to the nearest ship or landfall.
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