Flying to Mexico City – Part Two

ATP has graduates of our flight training programs flying for virtually every airline in this country, and once in a while they write to share what their flying jobs are all about. Chris Carey is an exceptionally talented pilot who writes from time to time to tell us what it is like to live the dream of being an airline pilot here in the United States. The following is the second part of a three part story about a day flying for the airlines:

There are two methods that can be used when flying a modern airplane into an airport such as this. The first method is to program all possible information into the computer. This includes altitude restrictions that must be met as well as desired speeds. The Flight Management Computer, known as the FMC, will then use that information to determine when the airplane should descend and also when it should begin various speed reductions. In a perfect world with no other traffic, this works well and is desirable as it allows the airplane to stay high as long as possible thus saving fuel. Experienced pilots know better though than to rely on computers in an environment such as this. The other, older method of flying is to manually set altitudes into the mode control panel on the airplane and begin descents when the pilot feels that it is appropriate. Most pilots operating into Mexico City use this method as it allows the pilot to have much more direct control over the airplane and to begin descents much earlier, a fact which can be crucial in Mexico. For our flight tonight, the captain and I have elected to use the older, more mechanical method. Regardless of which method is used, pilots are still responsible for ensuring terrain clearance at all times, something which is extremely important when operating in the vicinity of 18,000 foot mountains and trying to balance the need to descend and reduce speed while still maintaining legal terrain separation.

Roughly in the area of the PAZ VOR we ask for and begin our descent. The controller’s instructions are to descend to FL 300, or 30,000 feet. A quick check of the enroute chart shows us that this altitude meets the Minimum Enroute Altitude (MEA) for this route so I dial 30,000 into the airplane and select a mode that will give us an idle power descent to this altitude. As we near our new altitude we are now in the vicinity of the DATUL intersection which means that we can transition from using the area chart for navigation to the 10-2 arrival chart. Looking at the chart, one can see that at 60 miles from the Lucia VOR we should be at 280 knots and at flight level 300 (30,000 feet), which, thanks to our previous descent clearance, we are. Just as we are crossing the sixty mile ring, the controller clears us for the arrival which means that we can descend at will down to 12,000 feet but we must obey the crossing restrictions and minimum altitudes along the way. Our next crossing restriction is the 30 mile ring from Lucia which we are to cross at 250 knots and between FL 250 and FL 230. Since we are now inside the sixty mile ring, we are legally allowed to descend to this altitude which I elect to do immediately. Large jets like to either slow down or go down, but not both, so it is imperative to stay ahead of the descent path required. Many times in this area we will receive either a turn off course or a speed reduction due to spacing with another airplane which further complicates matters. Tonight we are lucky though and remain on course.

The third part of Chris’s flight will be on PilotJobs tomorrow.

Chris’s narrative will continue tomorrow on PilotJobs.com.

© 2011 by Christopher P. Carey

The views expressed here belong solely to Chris Carey and are in not endorsed by Continental or United Airlines.