When things go wrong, lack of information often adds to our frustration. Our undercover pilot sheds light on what’s happening behind the scenes.

Flights are often booked months in advance, with clearly stated schedules, so it’s reasonable to expect they will depart on time. Unfortunately, as you’ve all no doubt experienced, that’s not always the case.

What makes matters worse is when there is no staff to offer any information, leaving passengers disgruntled. As crew, we get equally frustrated by delays. We, too, want to reach our destination on time.

Some delays are known about ahead of time, such as planned strikes, so airlines can at least try to reschedule you and minimise the disruption. But in most cases, delays are caused by unforeseen issues such as adverse weather conditions, technical problems, air traffic control issues, passenger-related delays, knock on effects of previous flights, and crew hours expiring.

Failure to launch

In the UK, most weather-related delays occur in winter, as a result of fog, ice, snow, high winds and thunderstorms, but summer can also present challenges.

In all of these cases air traffic control (ATC) may need to impose restrictions on the number of aircraft departing and arriving, which at a busy airport like London Heathrow, can quickly create significant delays or cancellations.

The main challenge with fog is visibility for aircraft on the ground, meaning it takes much longer to vacate a runway on landing, and requires increased spacing between arriving aircraft. It’s also difficult to see other aircraft, so the number moving around the airfield has to be reduced.

Any deposits of ice and snow on an aircraft, meanwhile, will increase drag and decrease lift, which could be a recipe for disaster. The need to remove these deposits is therefore imperative, and achieved by spraying the aircraft with a hot fluid, which adds time to the normal departure.

High winds also result in delays as they destabilise aircraft landing which can lead to a “go-around” (see What goes around comes around), hence ATC restricts the number of landings to accommodate this. Thunderstorms also mean aircraft have to change route, which increases the ATC workload and requires the number of aircraft to be reduced to avoid overload.

Before departure, standard system and safety checks are run to ensure all systems are go. It’s not uncommon for minor technical issues to be detected. These usually pose no threat to passengers, but may require time to reset or require an engineer to fix the issue.

Other issues could be to do with the aircraft being too heavy. Each aircraft has a maximum takeoff weight (of combined fuel, cargo, passengers and so on), which varies depending on atmospheric pressure. If the aeroplane exceeds this, it cannot take off until the weight has been reduced.

Passenger-related delays usually result in baggage having to be off-loaded, which can take up to 30 minutes depending on aircraft size. In other cases, delays could be due to unruly passengers who are intoxicated or posing a threat to others.

Knock-on delays are another common culprit. There is only a finite time between an aircraft arriving and departing, which can be less than 30 minutes for some low-cost airlines. If the inbound flight arrives late, your flight is likely to depart late.

Chain reaction

Things happen – we get it. But why can’t airlines give clearer answers as to how long your flight will be delayed? Well, any one of these hiccups can lead to another, and another…

A technical delay requiring a simple fix may turn out to be more complex than originally thought. Because you’ve missed your air traffic departure time slot, another will need to be requested, putting you at the back of the queue.

The next thing you hear is that the crew are going out of hours. Crew are legally capped in the length of each duty to ensure the flight can be operated safely without crew becoming fatigued and making mistakes. A significant delay might push the crew over their maximum hours, which means new crew may have to be sourced resulting in a longer delay or cancellation.

If you are affected by delays, you can apply for compensation under the EU261 (UK261) regulations and could be entitled to up to £520. And please try not to shout at the crew – it’s most likely not our fault, and we’re just as fed up as you!