North Atlantic Error Summary, 2015

Just like everybody thinks THEY are an above average car driver when driving around the city, most of us just KNOW that a oceanic error will happen to the other pilot. Part of making this assumption a reality is to know where the threat is.

Approximately 460,000 flights cross the North Atlantic each year. The NAT Central Monitoring Agency is located adjacent to the Shanwick Oceanic Area Control Centre, in Prestwick, Scotland. Operational performance monitoring is one of the principle tasks of the NAT CMA. The primary source of operational safety reports are the air traffic control units responsible for the Oceanic Control Areas in the region, augmented by operator reports as available. The reports are reviewed by the CMA and a de-identified summary is available at year’s end. Here are some of the "Threat Vectors" I pulled from the latest 2015 report.

What is Reportable? 

  • Gross Navigation Errors (>25NM from cleared route)
  • Lateral Deviations of Less than 25NM
  • ATC Interventions to Prevent Lateral Deviations
  • Large Height Deviations (+/-300ft from assigned Flight Level)
  • Erosion of Lateral or Longitudinal Separation
  • Time Errors (3 mins or more between ETA and actual time at a boundary or waypoint)
  • Speed Errors – any change of Mach No. or speed that results in a Time Error as above
  • Air Traffic Control inter-agency coordination errors
  • Communications failures
  • Non–approved (MNPS and/or RVSM) or inappropriately equipped aircraft flying at RVSM levels
  • Diversions & Turnbacks
  • Adoption of a published contingency procedure


What was Reported in 2015 ?

  • 375, Total number of aircraft off their clearance... That’s more than one per day!
  • 119,  Large Height Deviations. More than 300’ off your assigned FL 
  •   97, ATC Interventions to prevent a deviation, ADS-C,CPDLC,read back, radar vectors
  •   86,  Lateral Deviations <25nm. Tracked for statistical data by the CMA
  •   30, Longitudinal Separation Erosion.  < 7minutes actual between aircraft 
  •   12,  Lateral Deviations >25nm. And reported to FAA for investigation
  •   10,  Time Related Incidents. A Conditional Clearance caveat missed typically

Who was Reported in 2015 ?

  • 305,  Commercial Airlines largest volume of traffic
  •   43,  Larger International GA, turbojet bizjets
  •   10,  Military, Almost all were USAF transports
  •     9,  Smaller International GA, KingAir, SR-22

Where were these Reports Located ?

  •   284,  Random Routing. SE corner of Shanwick OCA = Hot Spot
  •     73, Organized Track System. Even split between East and West bound
  • 205, Shanwick OCA, 83% of the deviations!
  •   77, Gander OCA
  •   50, Reykjavik OCA
  •   21, New York OCA
  •   17, Santa Maria OCA


Who were Positively Responsible ?

  •   89,  Aircrew
  •   29,  ATC


What were the Causes?

  •   70,  Followed flightplan instead of the clearance
  •   30,  Did not comply w/ Conditional Clearance
  •   15,  Weather Deviations, w/ Correct procedures
  •   15,  ATC blunder errors
  •   14,  ATC coordination errors
  •     1,  Medical diversion, This seems very low


Where did the Communication Come From ?

  •   94,  Datalink, Think; AFIS/ACARS
  •   61,  CPDLC, Think; FANS
  •   42,  VHF, Think; Airborne from aero-radio relay


When did the Errors/Deviations Occur?

  •   25-35 Per month until summer
  •   50-60 Per month in June and July, 2X "Average"
  •   25-35 Per month until end of the year



  • 1. If you are operating in the NAT...
  • 2. In the Southeast corner of Shanwick OCA...
  • 3. Flying an airliner or BizJet...
  • 4. On a Random route...
  • 5. Received your oceanic clearance via AFIS/ACARS
  • 6. In the months of June or July...
  • 7. And your SOP compliance is weak...
  • 8. You know you are on the assigned FL
  • 9. And you know you are a above average pilot
  • 10. Expect to have some explaining to do when you get home...or worse.