Thursday, 27 November 2014


(Extracts from EASA GA Safety Team ‘Weather Anticipation’ leaflet)

·    Understand weather patterns and their likely effects on your flying
·    Never fly without an aviation forecast!
·    Look for and consider PROB, TEMPO, OCNL and ISOL
·    Expect conditions to be about 30% worse than forecast!
·    Check actual conditions against the forecast
·    Identify alternative routes and suitable diversion aerodromes
·    Carry enough fuel
·    Scan the sky and horizon for possible problems
·    Avoid suspected or reported thunderstorms by at least 10 nm
·    Note local surface winds
·    Check weather reports whilst flying
·    Be prepared to divert

·    Aerodromes with FIS have a duty to provide pilots on request with METARs, SPECIs and TAFs, so ask for these whenever conditions are less than perfect
·  Check the METARS for your destination and possible diversion airfields every half hour before you depart (and en route if possible)
·   Tune in to airfields nearby which have ATIS to obtain likely conditions at your own field
·   Tune in to VOLMET broadcasts from time to time to get a broader picture
·  Take note of any TREND broadcast at the end of a report which denotes a  deterioration in visibility, cloud base etc.

·   Lowering pressure suggests possible worsening conditions
·   Surface wind speed or direction change occurring earlier than forecast can denote change of speed in the approach of a front
·   In Summer, wind changes can indicate nearby showers or thunderstorms
·   In Autumn or Winter, temperature and dew point comparison can indicate a likelihood of mist or fog, before visibility noticeably deteriorates
·   In the cruise, cloud below you (particularly in valleys) can indicate a potential fog hazard close to the ground



1.      Pilot

A pilot must make decisions about competence, current health, mental and emotional state, level of fatigue, etc. If a pilot is called early in the morning to make a long flight after only a few hours of sleep it would be prudent to consider if the flight could be accomplished safely.

A pilot with only 4 hours of sleep the night before was asked to fly to a meeting in a city 750 miles away. The reported weather was marginal and not expected to improve. He assessed that it would not be wise to make the flight. His boss was initially unhappy, but later agreed that the risks involved were unacceptable.

2.      Airplane

A pilot will frequently base decisions on his/her evaluation of the airplane, such as performance, equipment, or airworthiness.

During his pre-flight check, a pilot noticed a small amount of oil dripping from underneath the cowling. The quantity seemed insignificant, but the pilot decided to delay take-off for a mechanic to check the source. The pilot’s good judgment was confirmed when the mechanic found that one of the oil cooler hose fittings was loose.

3.      Environment

This covers many elements not pilot or airplane related, including weather, air traffic control, navaids, terrain, temporary conditions around take-off and landing areas, and surrounding obstacles.

A pilot was landing a small airplane just after a heavy jet had departed a parallel runway. He assumed that wake turbulence would not be a problem because of runway separation. Due to prevailing winds and the wake turbulence from the jet drifting across to the landing runway, the airplane made a heavy landing. The pilot had made an error when assessing the flight environment.

In practice

The interaction between pilot, airplane and environment is influenced by the purpose of each flight operation. The pilot must decide on the desirability of undertaking or continuing a flight as planned, by questioning why the flight is being made, how critical it is to maintain the schedule, and if the trip is worth the risks?

1.   On a ferry flight to deliver an airplane in marginal weather conditions, the pilot calculated the groundspeed and determined that he would arrive at the destination with only 10 minutes of fuel remaining. He was determined to keep on schedule by trying to “stretch” the fuel supply, instead of landing to refuel.

After landing with low fuel state, the pilot realised that this could have easily resulted in an emergency landing if weather conditions had deteriorated further.

 2.   A private pilot with around 350 hours was ferrying an airplane cross-country. Due to time constraints, the pilot skipped both dinner the night before and breakfast on the morning of the flight, planning to have lunch around noon at a fuel stop. A descent was begun from 9,500 feet about 20 miles out, due to haze and unfamiliarity with the area. At pattern altitude, the pilot could not find the airport and after flying around the town at the four compass points he decided to check the Flight Guide, which was on the rear seat and not easily reachable. Power had not been increased since the descent to pattern altitude, and the pilot had been holding back pressure on the yoke. Whilst trying to retrieve the Flight Guide, a loud “bang” was heard. Looking up, the pilot discovered that he was only about 200 feet above ground level. Increasing power, he climbed and located the airport. After landing, it was discovered a fibreglass antenna had been hit, which damaged the leading edge of the left wing.

It can be understood how a series of judgement errors contributed to the outcome of this flight:

  • The pilot was aware that fatigue and hunger could affect his ability to fly safely, but let the desire to stay on schedule override the concern for a safe flight.
  • The rush to get airborne led him to skip or postpone some aspects of pre-flight planning.
  • Research before take-off would have given a clear mental picture of the airport in relation to     the town. Studying charts and checking NOTAMs is part of careful pre-flight planning, and would have alerted the pilot to obstructions near the airport.
  • Good cockpit organization would have had the Flight Guide near at hand.
  • Flying around the airport area at traffic pattern altitude in hazy conditions has the potential for a mid-air collision.
  • The pilot’s first duty is to fly the airplane, which would include adjusting the power, setting the trim, and keeping track of altitude.

This pilot was extremely fortunate - the outcome could have been fatal.