Everyone hates aircraft delays. Passengers, crew, and the airlines themselves. The reasons for these delays can be: mechanical, weather, passenger (Yes your fellow passenger !), Air Traffic Control, catering, crewing, or baggage and cargo loading.
I will try and discuss each of these reasons (excuses?) for a delay.
Mechanical...You might drive your car with a flat battery, but a respected airline will not. Large passenger jet planes have plenty of built-in redundancies, but every now and then the dispatch guide states that something just has to be fixed. I told my passengers that the average car drives 100,000 kilometres in 6 years, whereas the average B747-400 travels this distance in one week. (100,000 km is about 62,500 miles). Just think of the things that break on a car over six years. Things will break on a plane, even a new one. Typical of the built-in redundancies is the air-conditioning systems. On a B747-400 there are three of them. Whilst in flight if two failed, as a passenger you wouldn't feel any difference. However before the plane could depart one of the broken systems would need repairing. Oh yes, while I am talking about air conditioning, pilots receive the same air as the rest of the plane. They do not get extra oxygen. The only real difference is that the cockpit does have its own temperature control. So the final word on mechanical delays is that no pilot is going to fly a plane that is unsafe. Your safety comes first!
Weather...Sometimes weather such as thunderstorms or snow storms make it unsafe to take-off or land. So the prudent pilot will wait until it is safe.
Passengers...It might seem strange to you to know that by far the most common source of delays is your fellow passenger. I would guess that 90% of my delays have been waiting for just one last passenger to join us. There are many reasons why passengers do not make it on board on time. Last minute shopping, getting lost in the terminal, making a telephone call. It is just a lack of courtesy. My airline has a policy that if a passenger is late boarding then a search for that person's baggage is commenced. If the bags are found first they are off-loaded, the doors are closed and we leave without the passenger. So make sure you are on board on time!
Air Traffic Control...The function of Air Traffic Controllers is to provide a safe flow of planes along the millions of airways around the world. Jet planes flying above 25,000 feet are always separated vertically by at least 1,000 feet, more commonly 2,000 feet, and along track by at least 30 miles (48 km). Air Traffic Controllers are responsible to maintain this separation, so sometimes your flight will have to wait to be able to fit in with the traffic flow.
Catering....A typical catering delay is when an incorrect number of meals has been loaded on board the plane. It must be a lack of communication that causes these delays. Either the passenger numbers change late or because airlines use an outside source for the catering. Which ever, delays will occur. Yes, I did delay a flight if there was insufficient catering. I believe that all customers are entitled to everything that they have paid for.
Crewing....This is usually caused by a crew illness or unavailability. The only crew delay I have experienced occurred about 44 years ago, while I was a junior co-pilot, when the Captain's father died just prior to departure.
Baggage and Cargo Loading...These are very frustrating because you never really know how long it will take to complete loading. The reasons for late loading can be weather related, last minute passenger joining the flight etc. On a B747 trying to load 400 passengers' bags can take more than an hour. Be patient, it is most important to leave with everyone's bags on board
If you experience a delay there is nothing that you can do about it. Believe me that pilots and airlines want the plane to leave on time too, but will only do so when it is safe to go. Try and not let something small like a delay ruin your flight. When booking your flight be careful to avoid flights with tight connections. It will incovenience you if your flight suffers a delay.