Tuesday, 2 October 2012

Close-ups of the contrail gap area

I made these two short videos during UA935 flight LHR-LAX on December 6 2011. They are taken from a seat 39A window at the rear of Boeing 777, the first video when approaching Greenland and the second one after crossing the Canada-US border in Minnesota. 

In the first video, condensation of water vapour from the engine exhaust is clearly visible probably due to colder air outside. Also, it is illuminated by the sun and stands out agains the cloud background:  

In the second video, condensation is less apparent but is still visible:


Wednesday, 18 April 2012

Первый блин

Recently, Ars Natura posted on the ContrailScience website a link to his blog with the "pictures of the erratic flight of a plane leaving a trail".

I have reconstructed from his photos the contrail and the aircraft flight path on Google Earth.

Firstly, I have found the exact locations of both viewpoints on Google Earth and checked them on Google StreetView. These viewpoints are about 16 km /10 miles apart. Secondly, I have added the photos, using identifiable ground features in them. Thirdly, for each added photo I iteratively have modelled the contrail so it would approximate the contrail image:

It is said that about 10 minutes past between the first and the second photo. As seen from above, in this period of time the contrail (white line for the first photo and cyan line for the second one) was blown away in SSE direction by about 16 km /10 miles, that is, the upper air moved with the speed of a car, about 100 km/h / 60 mph. Taking the wind into account, I have deduced  from the white model of a younger contrail a probable flight path of the aircraft (shown in red line): 

The wind direction and its speed is consistent with what can be deduced from the satellite images of the day.
In particular, the cirrus fall streaks in the high resolution Aqua image emphasise the wind direction (along the coast, toward the Africa).

The aircraft came in the direction from the Canary Islands and made a teardrop loop above the Gulf of Cádiz. It is not a predefined holding pattern for any of the nearby airports (Seville, Jerez and Faro). Perhaps, it was a cause of the "casualties" on the nearby US Naval Station Rota on the day.

UPDATE 14/05/2012

It looks like I finally have found the most likely culprit. It is a prototype of the Airbus Military aircraft A400M based in Seville. Its test flights can be followed on flightradar24. Having watched the air traffic in this area for a while, I eventually have got it flying a similar 'erratic' route above the Gulf of Cádiz: