Feb. 19, 1951; Near Mt. Kilimanjaro, Kenya (BBU)
7:20 a.m. An unknown object was seen by the crew and passengers of an
East African Airways "Lodestar" plane. The object was bullet-shaped
with a fin at one end. It appeared to be about 10,000 feet above Mt.
Kilimanjaro and hanging motionless. After about 17 minutes the object
began to climb rapidly and moved eastward toward the coast. Captain J
Bicknell, Master of the plane, obtained the signatures of all nine
passengers to a document stating they had personally observed the object.
The accounts say that the object looked like a white "star" to the naked eye, and seemed "incredibly distant". The shape was only seen in "powerful field glasses". Time was near dawn. The sky was crystal clear. The silvery speck was quite low in the sky (it seemed at first to be above 20,000-ft Mt Killimanjaro, but from an aircraft probably at comparable height this is not a high elevation angle). It appeared to be "absolutely stationary" at first but then climbed and disappeared after about 20 min.
First suspect here surely has to be Venus. Venus was rising low on the eastern horizon at the time (in an extraordinary close conjuction with Mars, in fact). The object seemed to climb and disappear "to the East". Any reasonable sceptic is going to "triage" this one as a probable Venus and prioritise effort accordingly.
But this would turn out to be quite wrong. Here's how I found out I was wrong.
The plane was a Lockheed "Lodestar":
Design and development and Operational history
The prototype of the Lockheed Model 18, which first flew in 1939, was constructed from one of a batch of Lockheed Model 14 Super Electras which had been returned to the manufacturer by Northwest Airlines after a series of crashes of Model 14s. The fuselage was lengthened by 5 ft (1.5 m), enabling the fitting of two more rows of seats and hopefully making the aircraft more economical to operate. However, most US airlines were by then committed to purchasing the Douglas DC-3, and Lockheed found the Lodestar difficult to sell at home.
A total of 625 Lodestars of all variants were built.
Overseas sales were a little better, with 29 bought by the government of the Netherlands East Indies. South African Airways (21), Trans-Canada Air Lines (12) and BOAC (9) were the biggest airline customers. Various Pratt & Whitney and Wright Cyclone powerplants were installed.
PLANE HEADING and OBJECT AZIMUTH
The Lodestar took off from Nairobi heading for Dar es Salam or Mombassa (possibly the former via the latter), which suggests a heading between SSE and SE. The object was spotted 20 min into the flight at 0720 so at 200 mph the plane would be some 60 mi from Nairobi and well into its cruise. The report says that on first sighting they were "heading roughly towards it" and it appeared to be "10,000ft above Mt Killimanjaro". That doesn't necessarily mean directly over the peak, which could be cited only as the most obvious height gauge in view at the time, but it seems likely it was generally speaking in the direction of the mountain. The mountain would have been about 60 mi roughly due S of the plane at this time, to the right of the nose. The rising azimith of Venus would be nearly 90 degrees away, in the East, to the left of the nose.
Of course the instant heading is not known with certainty, and the fore-aft axis of the aircraft is not necessarily coincident with the heading if there are strong winds. The bright, clear, cloudless morning does not suggest winds so strong that the crabbing angle would be significant. But maybe the heading was more ESE than directly SE to Mombasa for some reason? That would put Venus off the nose just a little to the left of the heading. But it would still be nowhere near Mt Kilimanjaro, of course, now off the right beam. The report says that the passengers began watching it after being alerted 3 minutes into the sighting, during which time it had been "absolutely stationary", so presumably it was still "above Mt Kilimanjaro", and because of cabin visibility the fact that the passengers were seeing it tends to prove that "above Mt Kilimanjaro" - however elastically interpreted - can't have meant "a little off the nose"
Lockheed Lodestar cockpit from passenger compartment.
Visibility forward from passenger windows is extremely restricted, and passenger visibility forward through the cockpit windows would probably be completely blocked except for a possible narrow view to a high elevation through the flight deck door - the flight deck is enclosed and its windows are at a much higher level than the passenger seats.
All of which suggests that if the passengers were watching and filming the object then it must (by that time at least) have been quite significantly to the left or to the right of the nose, not a small angle. Therefore if it was even in the same half of the sky as Kilimanjaro it must have been unambiguously to the right of the plane and thus very far away from Venus.
The North side of Kilimanjaro from 12,000ft.
The Lodestar took off from Nairobi at 0700, presumably LCT. Times given are therefore presumably Nairobi time. There's no summer/winter time in Kenya to confuse us. Nairobi time would be just GMT+3.
The object was spotted 20 min into the flight at 0720 so the plane was already at cruise height, probably about 20,000ft (ROC to 10,000ft 6.6 min; service ceiling 25kft), roughly the same as the summit of Killimanjaro. The object appeared to be about 10,000ft above Kilimanjaro, implying an elevation about 45 arcmin above the *astronomical* horizon (horizontal tangent plane containing the observer's eye).
At at 0720 Nairobi time (GMT+3) Venus would have been well below the apparent (terrestrial) horizon. It would rise around 0815 for an observer in Nairobi. The plane's altitude makes a difference of course: the dip angle in arcminutes is approximately the square root of the height above the ground in feet, so ~140 arcmin or 2.3 deg. This brings the rising time of Venus forward, but it still would not clear the local horizon until nearly 0800, after the observation had ended. The angle necessary to put Venus near the observers' astronomical horizon (significantly above an approximately co-altitudinal mountain peak) is far too large for any possible mirage refraction.
If the object was indeed seen in the south, in the vicinity of Mt Kilimanjaro, then the 3 min of motion before disappearing "to the East" at the end of the sighting was significant transverse motion, not merely apparent recession in the line of sight.
A stationary "white star" low in the morning sky with shape only resolvable in "powerful field glasses" and appearing as a silvery oblong does make one suspect Venus. A crescent Venus lying almost on her back could appear as a silvery oblong with a "fin" at one end. But again, as soon as you put numbers and details in the theory it falls apart.
Venus' phase on this date was 0.92, or almost full, nowhere near crescent.
The late time of rising gives a clue to one extremely strong reason why this could not have been Venus: If Venus is above the sun and rises in early twilight then it is prominent. In this case it was almost directly below the sun, and would have risen into a brilliant daylight sky. Extinction and scattering low on the horizon would make even a brilliant Venus totally invisible in this position, and on this date Venus was not even especially brilliant (magnitude less than 3, about 2.6 IIRC but I didn't make a note)
And Venus was not only the wrong shape it was the wrong size, only about 11 arcsec across. How "powerful" were those binoculars? They were in the possession of a passenger. The highest magnification binoculars in common civil use would I suppose be 12x (50 or 60) in which Venus could subtend an effective 2.2 arcmin. But this is still falling below the theoretical lower limit of resolution of shape (about 3 arcmin, or not too much less). In conditions of exceptional clarity, contrast and acuity, perception of a shape (never mind that it is the wrong shape for the phase of Venus!) might be possible. However according to the account the description of Capt Bicknell was very much more detailed than just a rough shape: the object appeared "sharp" and "distinct" in outline, was bullet-shaped with "vertical dark bands at regular intervals" ** and a square-cut fin at the end. This sort of resolution of internal details implies an effective angular size perhaps an order of magnitude larger than Venus in 12x binoculars.
No other astronomical object is remotely possible of course (the moon was tens of degrees under the horizon in the NW). What else could it have been? Who knows...? I suppose the lesson is: The most obvious simple explanation is not always the best one.
[** reminiscent of the vertical dark band on Capt Bowyer's bright yellowish cigar over the UK Channel Islands in Apr 2007?]