Of all the places to which I travel, one of my favorite and most challenging destinations is Mexico City. Mexico City sits at the top of the world, 7,300 feet to be exact, and is nestled in the Valley of Mexico between mountains that reach up to 18,400 feet. It is an ancient city founded under the name Tenochtitlan by the Aztecs in the year 1325. With the Spanish came change and in the year 1585 the city officially became Le Cuidad de Mexico, Mexico City. The city boasts antique Spanish architecture, cultural attractions in abundance and some of the best food one could ever hope to sample.
Mexico City is served by Benito Juarez International Airport, which is commonly called Mexico City International. The airport is the second busiest in Latin America after Sao Paulo, Brazil. The airport, like the city itself, is bound by mountains on all sides. The combination of mountains and high traffic volume results in one of the most challenging airports in the world.
Planning for an approach into Mexico City begins roughly two hours before our arrival. At this time, the captain and I retrieve all of the charts necessary for our arrival at the airport. These charts include, but are not limited to, the Latin America 3-4 High/Low altitude chart, The Mexico City area chart (10-1), the Radar Minimum Altitudes chart (10-1R), the Datul Two Alpha Arrival chart (10-2), the ILS DME Runway 5 approach chart (11-2) and the airport diagram (10-9). There are additional, company specific charts, but these initial charts are the minimum needed to operate into the airport. At two hours out we are still over the Gulf of Mexico and are just getting handed off from the controllers in Houston to Monterrey Center. Pilots always pay close attention to air traffic control and especially so when speaking with foreign controllers. The controllers in Mexico are great, but there is always a bit of a language barrier that must be overcome. Our route in Mexican airspace appears on our paperwork as COKER.UA649.PAZ…UJ55.DATUL… DATU2A. MMMX. This means that our route begins at the COKER intersection on UA649, which is a jet airway. Jet airways are just like highways of the skies: they are predetermined routes that help keep airplanes separated from one another. From COKER we follow UA649 until it ends at the Poza Rica (PAZ) VOR, a ground based navigation facility. From PAZ we follow another airway, UJ55 to the DATUL intersection, where we begin the DATUL Two Alpha arrival procedure, which is what provides us with guidance into the airport environment but not to the airport itself. Once in the airport environment, we will fly the Instrument Landing System (ILS) approach to runway five right (5R).
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.
We cross the thirty mile ring just as planned and check the chart for our next restriction which is to cross the Lucia VOR at 220 knots and between 13,000 feet and 16,000 feet. As mentioned earlier, it can be difficult to slow down at the same time as descending so we begin to deploy our flaps as a means to slow down the aircraft. At Lucia, we make a right turn to intercept and track the 219 degree course from Lucia to Mateo, another VOR in the area. We also descend another 1,000 feet to 12,000 and begin slowing to 180 knots which requires additional flaps. At this time we receive our approach clearance from the controller which allows us to use guidance from the 11-1 chart to take us all the way into the airport.
At the SMO VOR we turn outbound on the 160 degree course and begin our final speed reductions and configure the airplane for landing, all while descending to a new altitude of 9,700. At 9.2 miles from SMO, we turn left to intercept the localizer into the runway and descend to 8,800 feet, our last crossing restriction. Now at 8,800 feet, slowed back to our landing speed of 160 knots and tracking the localizer inbound to the runway we are all set up for the perfect approach to runway five right (5R) except for one thing. As often happens in Mexico City, the aircraft in front of us has slowed down more than a 737 does for landing and our spacing between the two airplanes is becoming minimal. The solution to this is instruction from the controller to break left and side step to a landing on runway five left (5L). As soon as I hear the controller issue the instructions, the auto pilot and auto throttles come off and I begin a descending turn to the left to line up with approach course to our new runway. There is no electronic guidance of any kind to this runway so it is up to the pilots to use their judgment and experience to fly the appropriate path to ensure a safe landing.
We land on 5L and use almost all of the 13,000 feet available to stop the airplane. The high density altitude of Mexico City means that our approach speeds are much higher than they would be at sea level thus our landing distance is greater. We exit the runway to the right and hold short of the other runway to wait for another landing airplane. After receiving taxi instructions to our gate and checking in with ramp control, we finally park the airplane at our usual gate 56.
Even though the captain and I have both flown this approach countless times, it is always challenging and requires the utmost care. It is airports like Mexico City that truly test a pilot’s ability and bring home the importance of always staying on top of the game. We are spending the night here tonight so there is time to relax and unwind before flying out the next day. No trip to MEX would be complete without a stop at Hector’s Restaurant to enjoy some classic Mexican tacos. If you really want authentic Mexican food, there is only one place to get it.
Chris Carey is a 737 First Officer with Continental Airlines, and former ATP graduate and CFI. Chris is a volunteer on the Pilot Career Coach forums at BeAnAirlinePilot.com, and frequent contributor to PilotJobs.com.