Why do Pilots do a walk around the aircraft before every departure?
Pilots are not Mechanics however before departure it is a required procedure for them to carry out a general inspection of the exterior aircraft before every departure. It is not an in depth inspection but a generic look out for certain issues or problems that could be obvious to the naked eye. If during the walk around a pilot witnesses something unusual, then they would call the mechanics for further clarification and/or inspection.
A typical Jet aircraft walk around inspection consists of the following:
- An inspection of the sensor probes e.g. pitot tubes, temperature sensors, angle of attack sensors etc. These should be free from any blockage/icing or damage.
- Inspection of the nose radome where the weather radar lies. Here again there should be no icing, damages or dents.
- General fuselage inspection for the whole aircraft to check for icing, damages or dents that could have been caused by for e.g. a bird strike on landing or previous takeoff.
- An inspection of the nose-wheel and main landing gear to check for no damages, leaks from hydraulic fluid, all locking springs and components are intact, oleo extension within limits, tyre condition, brake condition etc.
- Wing areas to include inspection of no fuel leaks, damages, slats and flaps, wing tip, lighting, no icing, etc.
- Engines - to include no leaks, fan blade conditions, cowls, icing, damages, exhaust section, etc. If you see something unusual then its always better to consult further with the commander and/or engineers.
- Tail plane section and APU area - Again to check for no damage, no leaks, icing, etc.
As a summary, the most important things to have in mind as a Pilot during the walk around of the entire aircraft is to ensure you don't spot any sort of dents/damages, Hydraulic or fuel leaks, Ice build up, Slats and flaps condition, Tail plane, lighting, wheels and gear bay including tyres, engines and sensor probes. If all appears satisfactory and normal, then pilots continue on to do their primary work in the flight deck and the commander of the aircraft can sign the walk around off in the technical log. Without this signature it is not legal to depart. Signing this means the commander accepts the aircraft based on what's already in the log book and checked by engineers and the exterior inspection adds no further remarks in it.
This was just generic overview of a typical aircraft walk around and based on what particular aircraft type you may fly, there may be further or additional checks that may be recommended by the aircraft manufacturer or by the company.
As a last note, please always pay great attention to your walk around inspection and remember if you see anything you are unsure about or unusual, then consult further with the commander and/or engineers before departure. If doing the inspection at night, do remember to use a good quality torch as it is easier to miss something in the dark.