How do pilots cope with delays?

We’ve all been there, spending hours and hours in the airport as the flight is delayed. How do pilots cope with delays?

In general, most delays are caused by either of the following:

Technical Problems
Weather Conditions
Air Traffic Control restrictions

All airplanes are checked by maintenance on a daily basis and before every flight by the pilots. This is important to ensure the safety of the flight. If a system malfunction or system alert arises during flight or on the ground, the airplane needs to be checked before the next flight. Pilots are not trained as mechanic, so the moment we notice a problem, we call our maintenance staff. The maintenance will look for the cause of the problem and fix the problem or replaces a part if required.

This, of course, takes time and whilst they are completely aware of the inconvenience it causes for the passengers, they can not rush their tasks. If it takes more time to solve a problem, the plane will be taken out of service and a standby airplane will be flown in to perform the flight. The broken plane can only go back to service if all problems are solved and all components are fixed. It then gets signed off by maintenance. In these circumstances, no matter how inconvenient for the passengers, safety has a higher priority than on time performance. 

Sometimes, the weather conditions are the reason for long delays. In case of Low Visibility for example. Not all airports are fully equipped for low visibility approaches. Arriving aircraft may need to divert to another airport if the visibility is too low to land. Take off may be delayed and the aircraft have to wait until the visibility is big enough for take off.

Strong wind. Even though aircraft can withstand a lot of wind, they do have limitations. The limitations depend on the direction of the wind and whether is steady or gusty. If the wind is out of limits, we are not allowed to land or take off until the wind slows down.

Thunderstorms are a risk for airplanes, both for lightning strikes and for the turbulence and icing inside the cumulonimbus clouds. If the thunderstorm is over the airfield, we may need to hold before we can land or divert to another airport. Refueling on ground is not allowed during thunderstorms.

In Winter Operations, with snow and ice, airplanes need to be de-iced and anti-iced before take off by ground staff. This could take a while, especially if all other aircraft are also in queue to be de-iced!

Snow and slush on the runway reduces the effectivity of the brakes (brake effect) and we can not take off with freezing rain or freezing fog.

Also in case of adverse weather conditions, we need to take safety in mind and not take any risks. We always need to take the rules and regulations established with regards to adverse weather and limitations into account!

ATC restrictions. Often, especially in summer, we get air traffic control slots. A departure slot means that we have to take off at a certain time. We can take off maximum 5 minutes before, or 10 minutes after our slot time. This slot can be at the scheduled departure time, but can also be two hours after the scheduled departure time. If we board the passengers, we may send a ready message, which means that if there is an opportunity to take off earlier, we can take off earlier and reduce the delay.

ATC restrictions are usually caused by limited parking availability at the destination or due to traffic congestion en-route.

And all of this happens while you are waiting in the terminal, and all you can see is the plane being delayed. Limited information is available and you don’t know how much time longer you will have to wait. The point is, that we in many cases don’t know that either.From our own experiences we know how annoying it can be to be waiting for a delayed flight without any information. The only thing we can do is maintain clear communication with our passengers, either by ourselves or via the ground staff and hope for the problem to be solved soon or for the weather to improve, so that we can depart as soon as possible.

And all you can see is the plane being delayed. Limited information is available and you don’t know for how long you have to wait. The point is, in many cases, that we do not know that either. We always try to give as much information as possible to our passengers and we do know from own experiences how annoying it can be to have a delay. All we can do is be patient, maintain clear communication with our passengers and hope that we can depart soon! 

 


How do pilots take off?

 

How do pilots Take Off?

To understand how an airplane takes off, we need to learn a little bit about aerodynamics. Aerodynamics is all about what happens when a solid object flows through a fluid. Air is a type of fluid as it can move freely around any object. Depending on the shape of the object, and in our case the shape of the airplane wing, the air will flow around it in a certain direction and causes forces on the wing.

The 4 forces acting on the aircraft, are thrust – lift – drag – weight. 

Thrust is the horizontal component pushing the plane forward, created by the engines.

Lift is the vertical component generated by the airflow passing the wings.

Drag is the horizontal component working backwards, which is the resistance force of the aircraft moving through the air.

Weight is the vertical component working downwards, caused by gravity.

If a plane is flying in the air, at the same altitude and the same speed, the thrust component is equal to the drag component and the lift component is equal to the weight component. 
But in order to accelerate, the thrust must be bigger than our drag and to climb, the lift needs to be more than the weight in order to go upwards.

The amount of lift generated depends on many variables. The formula for lift is the following:

L = (1/2) d v2 s CL

  • L = Lift
  • d = density of the air.
  • v = velocity of an aircraft
  • s = the wing area of an aircraft
  • CL = Coefficient of lift , which is determined by the type of airfoil and angle of attack.

This is where the shape of the wing (airfoil) plays a crucial role. Here you see a cross-section of a wing.

The shape of the airfoil splits the incoming air. The pressure of the air that flows on top of the wing is decreased due to the airfoils curvature and the air  pressure below the wing is increased. The airflow is deflected down and the airfoil gets pushed up, causing the plane to move upwards.

The more the airfoil changes the path of the incoming air, the more lift is created. The angle between the wing’s chord line and the relative wind is called the angle of attack.This is why the angle of attack the ‘pitch’ of the plane plays a part in the lift formula. You can see that the bigger the angle of attack, the more lift is created. 

If the plane pitches more downwards, the angle of attack is less. Less air gets split, less pressure difference exists between the upper and lower surface of the wing and the air is not deflected as much downwards as before. Because of this, less lift is generated. 

During take off, we increase the power of the engines (thrust) and the plane starts to accelerate. The wings will pass with a high speed through the air. The airflow around the wings is split, creating a lower pressure above the wing an a higher pressure below the wing. The pilots pull the control wheel to lift the nose up upwards. Lift will be generated and the plane starts going upwards and lifts off the ground. And we fly to our destination!