Scenario #2: A Navajo trip gets complicated.

You are an on-call pilot with a courier company that uses Piper Navajo aircraft to deliver packages for an over-night express company. The Navajo is approved for single-pilot IFR operations, provided the weather is above certain minimums and the autopilot is working. You are frequently called in during the winter to act as the co-pilot when the weather is poor or the autopilot malfunctions. In addition, you get the occasional flight when an extra charter is called for, or when a pilot calls in sick. You have slowly built up some experience on the Navajo, and the next time a pilot quits or gets fired, you will be on full-time.

You get a call in the middle of the afternoon from the company. There is a charter to fly into the interior of the province to deliver some urgently-needed medical supplies for the local hospital. You are asked to report to work immediately to do the flight. This trip is very exciting for you. Most of the flights the company does are short trips of an hour or less, the flights are pre-planned, and pre-filed, and you generally are in the right seat. This time you will be in the left seat on a longer trip that you will be responsible for. You wonder if this flight is a little test to see how well you handle the extra responsibility.

In the flight-planning room, some of the other pilots are clearly a little jealous about the trip that you get to do. The chief engineer walks in and asks you if you can do him a favour. He needs to replace the O-rings in the fuel selector and will need to drain the fuel tanks after your flight. He asks you to try to land with 45 gal. of fuel or less, so that he can drain all the fuel into the drum he has available. You know that the aircraft burns 32 gal. an hour in cruise, so 45 gal. will give you almost 90 min of reserve, which is more than enough.

The weather for the trip is quite good with some mid-level clouds, but no rain or snow in the forecast and most airports are reporting broken clouds based at 3 000 to 6 000 ft. It is the middle of winter so it will be cold at altitude but there is no icing in the forecast. The altitude for the outbound leg is 14 000 ft, so you need to make sure the oxygen bottle is filled up. The round trip will take just over 3 hr of flying and the fuel required for the trip, including allowances for start-up, taxi, and climb, exactly equals the fuel capacity of the two main tanks. This means that you can have 45 gal. in the auxiliary tanks for your reserve fuel. 

You go out to the aircraft and check it out. The oxygen bottle is half full. You have no idea how fast you will use the oxygen, but feel that it should be good enough for the flight since youíll only need it for 30 min on each leg. In addition, you recall how angry the owner was when another pilot had the oxygen tank filled up. Most of the flying done by the company does not require oxygen, so the owner had felt that the money had been wasted in filling the bottle for a single flight. 

The main tanks are almost dry, so you will need to have them filled. The auxiliary tanks are indicating half full, which gives 40 gal., or a 75-min reserve. You cannot confirm this level visually because of the shallow tank and the dihedral of the wing, but no one has complained of inaccurate fuel readings in this aircraft. This seems like more than enough fuel given the weather, the close proximity of an alternate, and the fact that it will be an evening flight with no ATC delays anticipated. Besides, with the weight of the cargo you will be carrying, and full tanks, you would be right at gross weight. Leaving the auxiliary tanks half full will keep you lighter and give you better performance for the climb over the mountains.

You call up the fuel company to service the aircraft. What do you ask them to do?

 Fill up the main tanks, auxiliary fuel tanks, and the oxygen tanks. The chief engineer and the owner will be angry, but you donít want to run out of either fuel or oxygen. Also, performance wonít be quite as good for the climb, but at least you will know exactly how much fuel you have.

Fill up the main tanks and add 5 gal. a side to the auxiliary tanks. That way you carry as much reserve as you can, while still keeping the chief engineer reasonably happy. The oxygen isnít too critical since you feel confident that the half tank will last for both legs, but you can monitor the use of oxygen on the way up, and if there is a problem, you can make alternate plans once you are up there.

 Fill up the main tanks.  The owner and the chief pilot will be happy.  You get the best performance out of the aircraft, while still carrying over an hour of reserve fuel.  The oxygen isnít too critical since you feel confident that the half tank will last for both legs, but you can monitor the use of oxygen on the way up, and if there is a problem, you can make alternate plans once you are up there.