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Maximum Range

Apologize for not writing for a long time, but I had a few days off and was rather busy at home. I now started a new work period from Oslo. I was assigned a flight to Las Palmas on the Island of Gran Canaria. These kind of holiday flights are usually always fully booked. This flight is on limit of the range of the A320 and we were also supposed to fly to Las Palmas and back again during one day. This means that we would be working for 13 hours, which is the legal limit for day time flights. Under certain conditions this can be extended to 14 hours in advance by the company. The company agreed to apply this procedure, because a minor delay would otherwise put us over the limit. If there is a delay during the actual flight that could not be foreseen (for example due to weather or unusual airspace congestion) that Captain can increase this limit up to 15 hours after consulting with his crew. This option however requires a written report to the authority, so I try to avoid this option unless absolutely necessary.

When I received the flight plan I noticed that the company had already used all legal possibilities to improve our payload. Today we were both limited by tank capacity and Maximum Takeoff Weight. The minimum required fuel for our flight today would be 18700kg, which is exactly the published tank capacity of the A320. There is a possibility to have one or more additional tanks installed, however this is rather uncommon and our airplane today didn’t have them. With the full load of passengers we had an estimated takeoff weight 76.9 tons, 100kg short of the structural limit of 77 tons. We use a special application on our iPads to calculate the loading. When I entered the values that I estimated before the flight I discovered an other issue. Close to Maximum Takeoff Weight the aircraft is also limited by the Center of Gravity, i.e. the distribution of the loading [1]. With only a few bags the airplane would be too nose heavy, with too many bags the airplanes would be overweight. We only know the actual amount of passengers and checked in bags after the check in closes a short time before the flight, so we decided to wait and decided when we had some real figures. In these situations a decision has to be made to either leave passengers and their bags behind or to make a fuel stop. However making a fuel stop would have brought up the issue of maximum working times. A fuel stop adds around 1 hour of delay and because there will be an additional flight the maximum allowed flight time is reduced by 30 minutes – so in our situation a fuel stop would likely involve staying in a hotel in Gran Canaria and canceling or delaying the return flight by around 12 hours.

When we arrived at the airport we were told that many passengers were children and we had 153 bags, which was more than I anticipated. We put the values into our iPad App and noticed that we were exactly on the Center of Gravity limit and around 50kg below the maximum takeoff weight. However with our fuel load we would just be able to fly at the most economic speed, i.e. slower than normally and the company also used a procedure that enabled us to reduce the additional fuel carried, but meant that we had a Decision Point [2], over the Atlantic southwest of Portugal, at which we needed a minimum quantity of fuel. If we didn’t have it at this point we would have to divert to Faro in southern Portugal, if we had this quantity at this point we could continue to Las Palmas.

We departed at just under 77 tons and headed towards the UK. With our low speed against the headwind we expected a flight time of just under 6 hours. Air Traffic Control asked us a few time to speed up for the benefit of traffic behind us, but we managed to negotiate to continue at a slow speed and we also managed to maintain our altitude as close to optimum as possible. When we approached the decision point after around 4 hours flight time we noticed that it would be tight. We had already obtained the weather for our destination airport. I was a typical day in the canary islands, 25°C and generally good weather but strong winds. Our alternate airport was also useable. We passed the decision point with around 160kg more than we needed and estimated to land at the destination with around 200kg above the minimum required reserves, i.e. around 5 minutes of flying time. If there was some issue at the destination we still had to option of diverting to our alternate Tenerife and 30 minutes of ‘final reserve fuel’. Luckily there was not much traffic in Las Palmas and we landed in the strong winds in Las Palmas after just under 6 hours in the air. During our descend we got a nice view of the Teide volcano [3] on the neighboring island of Tenerife.

Mount Teide as seen from the aircraft

When we parked we had around 2400kg in the tanks, the minimum quantity to make the decision to go to Tenerife would have been 2200kg.

We felt a bit tired after this flight, but on the way back we only had around 150 passengers and also a tailwind, so we were not limited on that flight and added some extra fuel. Due to our slow speed on the first flight we had some delay now, but we could compensate for this by going faster on the way back. With the higher speed and the tailwind we estimated a flight time of under 5 hours. The sun set while we were crossing into Portuguese airspace, but once we travelled further north we could already see some light just after midnight. The sun below the horizon was illuminating some clouds which reflected the light. This phenomenon is known as noctilucent cloud [4].

Noctilucent clouds over the North Sea

When we landed the sun hadn’t risen yet, but it was already really bright at around 2am. After this long and exhausting day we were all happy to go to sleep.

[1] Center of Gravity
[2] Fuel Planing
[3] Mount Teide
[4] Noctilucent clouds

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