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Sterile Cockpit

by Darren Smith, CFII/MEI
General Aviation Human Factors, Oct, 2008
Navigation:  Fundamentals of CRM | Resolving Conflict | Workload Management | Checklist Usage | Briefings & Callouts | Training CRM | Threats to Safety | Error Management | Integrating Threat & Error Management | What are you doing over there? | New Captain Series

On September 11, 1974, Eastern Airlines flight 212 from Charleston, NC to Charlotte, NC crashed just short of the runway killing 74 of the 78 passengers and crew.  The NTSB concluded that the accident was caused by the flight crew's lack of altitude awareness and poor cockpit discipline.

While the NTSB was investigating the accident, the investigators listened to the Cockpit Voice Recorder (CVR).  It was determined that the pilots of the accident flight had engaged in unnecessary and impertinent discussion of politics and used cars during the approach.  None of the call-outs required of the Captain were made indicating impending loss of situational awareness and/or workload saturation.  In fact, they were looking through the fog to find a visual checkpoint on the ground.  The NTSB's conclusion: The flight crew's lack of altitude awareness at critical points during the approach due to poor cockpit discipline in that the crew did not follow prescribed procedure.

The FAA educated flight crews that non-essential chatter during critical phases of flight, such as approach and landing, can distract pilots from flying duties.  In 1981, the FAA promulgated FAR 121.542/135.100 which states:

(a) No certificate holder shall require, nor may any flight crewmember perform, any duties during a critical phase of flight except those duties required for the safe operation of the aircraft. Duties such as company required calls made for such non-safety related purposes as ordering galley supplies and confirming passenger connections, announcements made to passengers promoting the air carrier or pointing out sights of interest, and filling out company payroll and related records are not required for the safe operation of the aircraft.

(b) No flight crewmember may engage in, nor may any pilot in command permit, any activity during a critical phase of flight which could distract any flight crewmember from the performance of his or her duties or which could interfere in any way with the proper conduct of those duties. Activities such as eating meals, engaging in nonessential conversations within the cockpit and nonessential communications between the cabin and cockpit crews, and reading publications not related to the proper conduct of the flight are not required for the safe operation of the aircraft.

(c) For the purposes of this section, critical phases of flight includes all ground operations involving taxi, takeoff and landing, and all other flight operations conducted below 10,000 feet, except cruise flight.

The rule clearly delineates activities which are required for the safe operation of the aircraft from the non-essential.  It also provides flight crews with a clear definition of a "critical phase of flight" -- taxi operations and flight operations below 10,000 feet. Subsequent research by the Flight Safety Foundation finds that 80 percent of incidents and accidents occur during these times.  This would indicates that compliance with this rule should be a flight crew priority.  Nearly 30 years since the rule was published, post crash CVR transcripts still reveal an abundance of non-essential conversation. 

Conversation is a powerful distracter.  NASA research into pilot deviations found that sterile cockpit non-compliance lead to the following errors: 
  • 48% had altitude deviations
  • 14% had course deviations
  • 14% had runway transgressions
  • 14% had general distractions with no specific adverse consequences
  • 8% involved takeoffs or landings without clearance
  • 2% involved near mid-air collisions due to inattention and distractions.
Sight-seeing, unnecessary radio calls or PA announcements, distractions from Flight Attendants, and unnecessary conversation are the activities which cause the most problems.  There are clear ways to resist the inevitable errors from these threats.

Avoiding the Threats

The first strategy in avoiding the threat of distraction is to set the proper tone in the pilot briefing.  Among the things that should be discussed should be the sterile cockpit rule.  Suggested briefing verbiage: "The sterile cockpit rule is important to me so we're going to use this rule to help us resist errors, is that ok?"

Another strategy that many airlines use is a single chime or an indicator light to let flight attendants know that we're above 10,000 or heading below 10,000.  The act of informing fellow crew members not only keeps them involved in the happenings inside the flight deck, it manages their expectations and sets the stage for sterile cockpit compliance.

Unexpected intercom calls during sterile cockpit should be greeted with the response, "Is there an emergency?"

In the absence of proper cues either with high altitude airports or cruise altitudes below 10,000, set a limit appropriate to the aircraft type you're flying.  The limit could be time, in minutes, to arrival, or distance from the destination.  With jets you might set a limit of 20 minutes or 50 DME and with props you might set a limit of 10 minutes or 20 DME. 

If you are using a technique to help you resist errors related to sterile cockpit issues, please drop me a note and let me know how you handle these threats. 

"Travelers are always discoverers, especially those who travel by air. There are no signposts in the air to show a man has passed that way before. There are no channels marked. The flier breaks each second into new uncharted seas."
— Anne Morrow Lindbergh, North to the Orient, 1935   

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