Planespotting Update

Over My House

From My Lawn Chair

Following up on the posting of March 14, 2014, Planespotting With Flight Tracker Software, the temporary routing of incoming planes over our house on their way to the Philadelphia Airport was rare this summer. It’s the old law of nature: when you don’t want something, it is always popping up, but when you do want it, it never seems to happen. But when they were flying over, I was there, looking up from my lawn chair with my Nexus tablet in one hand, binoculars in the other. I still have no idea why they change. They either fly overhead one per minute or none at all. The change is abrupt. Outgoing flights never seem to be funneled together that way. They quickly gain altitude and head off in the direction of their destination.

The low, incoming flights are the interesting ones. They are at an altitude of only about 3,000 feet. It is easy to imagine the passengers preparing for the landing.  The outgoing flights that occasionally pass over our house are already at about 10,000 feet and are too distant to relate to. Flights to and from cities other than Philadelphia are over 20,000 feet and are only specks or contrails in the sky. Often I cannot see them at all, but only faintly hear them.  And now, as we move into the cloudy days of fall, even the incoming planes are often obscured.

The app gives complete data on each flight, including the make and model of the aircraft. Perhaps 90% of the planes I see are regional jets seating less than 100 passengers.  They are the workhorse, medium-sized planes with two engines on the wings that I always assumed were standard Boeing models, but most are Airbus A300-series, made by a French company that is a consortium of several European companies. Another large number are made by Embraer, a Brazilian company I had never heard of.  A few jets have the two engines mounted on the fuselage back by the tail, as in the photo.  I occasionally see a McDonnell Douglas jet.  Once common, they are now rare, as would be expected since the company was acquired by Boeing in 1997.  Four-engine jets have almost disappeared as the engines become more powerful.

Most of the jets I see belong to USAir—Philadelphia is their hub—so I am not seeing a random sample of all commercial aircraft.

I did see one distinctive Boeing Dreamliner 787. The wings had considerable flex, especially out near the tips, that was very noticeable as it flew over the horizon on its way to Philadelphia, and the plane easily resembled a giant, soaring bird. It, too, had only two jets on the wings, both very large.

The Federal Aviation Administration is reportedly having trouble rolling out the new ADS-B tracking system that depends on GPS systems carried on-board each aircraft.  The trouble lies in the ground-based installations that gather the data radioed in.  Philadelphia was one of the few cited as having special problems.   The app also uses data from individuals who relay in the data from their own ADS-B receivers.  Somebody, somehow, must resolve conflicts, and occasionally an icon mysteriously heading off in the wrong direction disappears from the screen or suddenly zooms to a new position as if it were rocket propelled.

On one, the flight data came up “BLOCKED” which is permitted for security reasons.  Maybe that was Joe Biden.

The app also displays conventional radar data from the FAA, but with a 5-minute delay (they say).  Five minutes is a long time when tracking planes low overhead, and they are the ones whose identity I have to guess.

Commercial aircraft are not required to have ADS-B until 2020, and even that date is likely to be pushed back. Most already have it.  The app usually displays those correctly.  It should improve with time.  ADS-B stands for “automatic dependent surveillance-broadcast.”  You can read all about this at

With all this uncertainty, planes it shows as directly overhead are sometimes not there and planes that are overhead do not show on the screen. But all-in-all, I can identify about half the planes with certainty and intelligently guess at about another quarter, which is still fun.

Oops, here comes one now from Dublin.  How cool!


About Roger Walck

My reasons for writing this blog are spelled out in the posting of 10/1/2012, Montaigne's Essays. They are probably not what you think.
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