Views From the Air

Last week, Uncle Bob and I began the five-day (or more, depending on weather and who-knows what else!) flight back to the USA. We had prepared the airplane the previous day, re-installing the 20 gallon bladder that serves as our reserve tank in case a flight leg goes over about seven hours, and loading all except our personal baggage.

I had suggested that we experiment with significant aft loading to see if the less-stable configuration would manifest itself in improved cruise speed and fuel economy as theory predicts. To the extent that our crew and baggage weights allowed, we did this. I am awaiting a trip summary from Uncle Bob to see if a difference was noted. Other things, about which another posting may be released to reveal, took precedence over these more mundane calculations.

The first notable view (missing under clouds on previous trips) is of the jungle between Ribeirao Preto and Alta Floresta. This is in the Amazon basin and only in the early morning are such views possible; by afternoon, these little cumulus clouds have reached maturity, many becoming booming, bouncing thunder storms!

The views over the right wingtip and over the nose through the propellor are typical of my view as the c0-pilot and de facto pilot-in-charge as we cruised at an altitude of 12,500 (called "Flight Level twelve-five" in pilot and controller lingo -- FL12.5 for short). At times during this flight from Brazil to USA we flew at higher altitudes -- up to FL15.o during one or two legs.

The reason we were able to fly at these altitudes in Brazil was because our transponder was inoperative (more on that in a later posting!) so our altitude could not be monitored by air traffic control. However, this altitude was safer than the generally-stipulated FL09.5 for VFR flights witin Brazil because this airspace is vacant except for occasional airliners climbing or descending from or to a higher altitude. It is also significantly clearer of clouds (as the pictures show, this is above most cloud tops!) than FL09.5. The air is also much smoother.

One of the most fascinating phenomenon I saw was the cloud "rivers" which appear within the Amazon basin. These formations are the result of the air being cooler over a river than over the land on either side. The warm air rises and carries moist air into higher altitudes where is condenses to form clouds. Thus, when the wind is negligible, the clouds form only over the land -- this changes of course in the early hours before sunup when the land may become cooler than the water in the river. I don't know if that ever happens in the tropical jungles in the Amazon basin -- it always seemed hot to me!!

In fact, within two days' travel, we went from 10 or so degrees south of the Equator (Boa Vista) to 20-some degrees north of the Equator (Providenciale in the Turks and Caicos islands), and cruising at an altitude of 14.5, we encountered some clouds where the outside air temperature was 5 degrees Celsius below zero!! I caught cold -- the only sickness I suffered during this whole trip.