Evening star., 1952-08-24

to stay with them. Ultimately there
turned out to be no question Of the
friendliness Of the mysterious trio.
They turned out to be French Con-
stellation. q British Overseas Always
Corp. transport and a Pan American
World Airways Stratocruiser.
AL had properly cleared through
Gander, Newfoundland. and fight
plans had been passed on. in accord
ance with American procedures.
However. the fight had weather
trouble. Winds were different than
forecast, causing an appreciable de-
Walton from flight plan. The pilots
properly passed these deviations and
their new flight plans to Canadian
ground stations. But ground COM
munication failures prevented the
fight plan from reaching Presque
Isle. That little complication was
the trigger for this coun-ry-wide
alert.
At Ent there still was no Aews Of
the vapor trails of Nunivak. Gen.
Chidlaw personally had talked with
all his Air Defense Force command
ers. It was decided to call in the
Army Anti-Aircraft Command at
3:41 am. That command at once
sent out Its canned" message alert
ing all units on site to man their
guns. and other units to prepare to
move.
The whole country now was ready
for the Nuniyak menace. But the
night wore on and those mysterious
aircraft from the Bering Sea did not
arrive. The estimated time Of ar
rival-4:3O a.m.-came and passed.
When it looked like the threat had
abated, Gen. Chidlaw called OF the
state of air defense readiness. The
time was 5:42 am. The Nunivak
contrails never reappeared.
Lessons Leorned
The vital and fascinating business
Of accommodating the lessons and
problems exposed by the alarm still
is going on. It definitely has shown
the slim indications under which the
ADO will take action, and the speed
with which the ADO can act. Next
time, Of course. ADO may not have
the grace Of such advanced warning.
Vapor trails are unusual things in
this country, as explained by Louis
p. Harrison, chief, Technical 1nves-
legations Section, United States
Weather Bureau.
For each pound Of fuel used by an
airplane, the exhaust expels one and
q quarter pounds of water as the
result Of combustion. Water Yapor
from the exhaust and water vapor
from the air mix behind the aircraft,
he explains, and depending on the
temperature, condensation forms into
vapor trails. They come In three
forms. The exhaust type is the most
common. There also are convection
and aerodynamic contrails.
The weather in the Nunivak area
was especially suited for formation
of vapor trails. st. Paul'S and Bethel
Radiosonde Stations reported that
at $4,000 feet the night Of April II
the humidity was high and the tenn
perature was fairly low.
During the last war, vapor trails
were a matter of serious concern to
the Air Force. Bombers would leave
the big plumes behind them over
Germany, giving enemy fighters q
veritable road to follow in pursuit.
Vapor trails have been seen over
Washington, too. Early on the morn
ing of January 6, 1943, for exam
pie. a trail was left by a plane
which was not seen by the naked
eye. Newspaper switchboards were
jammed with calls from people want
ing to know what was in the sky.
This also happened over Springfield, ],
Mo-, in the fall of that year.
What were the vapor trails over
Nunivak? The spoilers of Alaska
could have had hallucinations. Or
the trails could have been made by
enemy planes that turned back.
Probably no one will ever know.