Variometer

There are strict regulations governing how much fuel planes must carry.

Flights operating under instrument fight rules, which basically all commercial flights do, must have enough fuel at a minimum to taxi to the runway and take off, fly to their destination, conduct an approach, carry out a missed approach, climb to altitude, fly to an alternate airport, conduct an approach there, fly for an additional 45 minutes, and also carry at least enough fuel to hold for 30 minutes at 1500 feet.

Avianca Flight 52 easily met all of these requirements, with enough fuel to stay in the air for 6 hours and 8 minutes.

At just before 3 o'clock local time, Flight 52 was ready to depart.

Although they were warned of low-level wind shear, the pilots didn't brief on what they would do if they encountered it while landing.

Much as it had been with their attitude towards the fuel, they figured that they would cross that bridge when they got to it.

Once the flight engineer was finished with the briefing, the captain and first officer continued setting up the navigation radios to pick up the instrument landing system for the runway.

Once lined up, they would use their instruments to follow these radio beams all the way down to the runway.

The pitot-static system is a combined system that utilizes the static air pressure and the dynamic pressure due to the motion of the aircraft through the air.

These combined pressures are utilized for the operation of the airspeed indicator, ASI, altimeter, and vertical speed indicator, VSI.

Figure seven dash one.

Impact pressure chamber and lines.

The static pressure is also delivered to the opposite side of the ASI, which serves to cancel out the two static pressures, thereby leaving the dynamic pressure to be indicated on the instrument.

When the dynamic pressure changes, the ASI shows either increase or decrease corresponding to the direction of change.

The two remaining instruments, altimeter and VSI, utilize only the static pressure, which is derived from the static port.

Static pressure chamber and lines.