Toluca - Oaxaca   7 - 8 April

It was quite a send-off at Toluca airport! Several of Jorge and Malu's aviator friends came to see us off and Jorge took off just after us in his 'Aguila Negra' Mooney Rocket to take some shots of us in flight.

After all the e-mail duties in the morning, and a further delay just before take-off - Flemming didn't realize that the flight plan hadn't been filed, as they only file it after one collects all the necessary stamps - we only took off at 2.15 p.m.  By that time the cumulus clouds and their associated thermals were omnipresent.

Besides the thermals, there was another major problem: the high density altitude prevailing at Toluca. At the time of take-off, the air temperature had risen to 25° C which amplified the problem. Toluca's elevation is 8,450 feet (2575 meters) above sea level and the air temperature was therefore 27 degrees above the temperature in the so-called standard atmosphere, - 2° C. The high temperature added 3,400 feet to the altitude resulting in a density altitude of 11,850 feet, very thin air indeed for a non-turbocharged aircraft. This causes a very significant decrease in engine power (down to about 55%) and to get adequate lift for take-off a much higher true airspeed is required to get airborne. Thus a very long take-off run would be necessary. Fortunately the runway in Toluca is paved and very long: 4200 metres. In addition, the highest elevation considered in Honey-Mooney's 37 year old aircraft manual is 5,000 feet! So we were in fact test pilots and our main reference was therefore past experience in hot and high density airports like Nairobi Wilson (elevation 5,500 feet but hot) in Kenya and Bryce Canyon, USA (elevation 7,600 feet and also hot).

Since the runway was so long, there was in fact no doubt that we would get airborne. The problem would be to stay airborne once we got airborne. The danger in high density take-offs is to get airborne at too low an indicated airspeed, which results in a high induced drag due to high angle of attack such that all available engine power is used to stay airborne and none is available for acceleration to a more optimum speed for climb. The difficult phase would thus be to accelerate from the take-off speed of 70 knots to the best rate of climb speed of 90 knots. Furthermore we would be quite heavy with almost 11 hours of fuel on board as there was no Avgas available in either Oaxaca, San Cristobal, Palenque or Chichén Itzá. Normally we take off with 15 degrees of flaps and rotate at 65 to 70 knots indicated airspeed depending on weight. Further acceleration on the ground is difficult as directional control gets difficult with little weight on the main landing gear.

After lining up on the long runway we applied take-off power, adjusted the mixture for best power mixture checking both fuel flow and EGT (Exhaust Gas Temperature), and then released the brakes. As expected, the acceleration was very, very slow and the take-off run seemed to take ages. To improve the odds for success, we made the take-off run with zero flaps, accelerated to 75 knots indicated and then suddenly applied take-off flaps of 15 degrees. The aircraft jumped into the air, we quickly retracted the landing gear and came back down close to the runway to accelerate in ground effect. We were accelerating, great!! Soon we could retract the flaps and we were at the optimum clean rate of climb speed of 90 knots well before we passed the departure end of the runway. We made it!! Another reference has been put in our logbook for heavy and high density altitude take-off in Honey-Mooney. Jorge, who was taking off just behind us, did of course not have any of these worries as his Rocket Mooney is equipped with a huge turbocharged engine producing close to two and a half times as much power at take-off. After take-off we were still struggling with the climb rate as we were flying toward rising terrain. There is a pass close to 10,000 feet about 15 NM to the south-east of Toluca which we had to pass, and the rate of climb varied between +600 feet to -200 feet per minute due to the thermals. Eventually we reached our intial cruising altitude of 10,500 feet. Needless to say, Jorge had no problem  catching up with us in 'Aguila Negra' so we could take some photos. 

Above 3 paragraphs by Flemming (as you can no doubt guess!).  Back to me:

The first 15 minutes or so while Jorge was accompanying us weren't too bad, but the turbulence due to thermals worsened after that and I was very unhappy for the rest of the flight.  The actual flying time was only 1 hour 40 minutes but it seemed interminable.  I was so relieved to get on the ground.

Another pilot, Enrique Morán, arrived in Oaxaca at about the same time as us.   He was interested to see where we came from and, of course, we told him about our world trip and that we had just been staying with the Mexican Earthrounder Jorge Cornish. Enrique is a pilot for a private air taxi company in Oaxaca.  He very kindly gave us a lift into town to the colonial style Posada Catarina with rooms arranged around attractive courtyards.  Then he said he wouldn't be on duty the next day (Monday) and would be happy to drive us to Monte Albán to see the Zapotecan ruins.

By this time we were both pretty exhausted from lack of sleep and the ordeal of the flight but in spite of that we headed for the main square called the zocalo and sipped margaritas while we absorbed the lively atmosphere of that beautiful colonial town.  This was Sunday and it seemed as though half the population of Oaxaca had come out to celebrate the day of rest.  There was music playing from the 'kiosk' (gazebo) in the middle of the square, children playing with balloons, shoe-shiners and colourful Indians selling their wares.  We strolled along the pedestrian street lined with handicraft shops and museums to the Santo Domingo church which looked splendid in the late afternoon sunlight.

The next day, Enrique and Carlos Rosales (another pilot and colleague) drove us in Carlos'  car to Monte Albán, the ancient Zapotec capital. Perched on the top of a mountain which was flattened when it was built, the ancient city has a dramatic setting and beats Chichén Itzá as far as that is concerned. It was inhabited from about 500 BC to 950 AD and was at its peak from 300 to 700 AD.

After that, we enjoyed a good late lunch/early dinner at the Casa de la Abuela on the zocalo that had been recommended by Malu and Jorge.  It's great in Mexico.  You can eat any time from 1 p.m. onwards.

As we stepped outside the restaurant, there seemed to be a mini street carnival going on with parades of people wearing huge masks.  There was even more excitement when one of the top-heavy masks toppled over and its bearer tried desperately to retrieve it.

Oaxaca had the best shops for arts and crafts I have seen in Mexico.  So after a successful shopping spree for Flemming's birthday present, we went to see a show of dances in the traditional costumes of the surrounding villages.   Each village has its own colourful costume and traditional dancing.  Flemming had his eye on the girl in the picture below.  I can't say that her partner with the cumbersome headdress held the same appeal for me!

Thanks:

Jorge and Malu Cornish, Enrique Morán and Carlos Rosales

At Toluca airport on departure with Jorge's 'Aguila Negra'  behind