August1999
Denniston recently talked with Pierre
Eckert, Centre Meteorologique, Geneve
(Geneva), one of the meteorologists on
the Breitling Orbiter 3 team who made the
first non-stop round the world flight pos-
sible. Following is part of that interview.
Why did you wait so late in
the winter seasontolaunch?
Pierre Eckert:The Chinese government
imposed a rule on all teams that they must
pass south of the 26thparallel. This con-
ditionisnot easyto reachfromSwitzer-
landwhichis around46degreesN.lati-
tude.Neitherwasiteasyfor theothers,
but we were more patient.We hadbeen
lookingsinceNovembertofindgood
starting conditions which finally appeared
on the first of March.
What were the conditions youwere
lookingfor?
PE:Firstweneededcalmwindcondi-
tions and noprecipitationfor 12 hours at
the launch site, Château-d’Oex, Switzer-
land.Ataltitude,wewerelookingfor
winds fromthe northwest, leadingusto
Egypt as quickly as possible. It turned out
that suchconditions wouldalways bring
the balloon quite quickly back to thenorth
inthe regionof the CaspianSea.Bythe
middle of Januarywe hadthe idea to try
another strategy, looking rather for winds
fromthenorthtonorth-east,headingto
Morocco. Thiswasto leave time for the
low over the Mediterranean Sea to vanish
or tomove eastwards.
When you did go for takeoff, howfar
ahead were you looking and what did you
see?
PE:Wegaveafirstwarningfourdays
beforelaunch.Takingintoaccountthat
we wanted to know a trajectory for about
five days,itmeantlooking9to10days
ahead. Whenwe made the final decision,
wewerequiteconfidentthatwecould
reachOman,ourintermediategoalfor
throughthesouthofChina,in
about five days.
When Orbiter wasover Mauritania,
thecoreofthejetstreamwasblowing
towardIraq, butlower it was blowingto
Saudi Arabia, further south. Can youex-
plain how that canbe?
PE:Thewindsalwayschange indirec-
tion and speedwith the altitude, just as at
loweraltitudes.Thewindsthatyoude-
scribe were true at thatmoment,but it is
notalwaysthecase.Anyhow,weknew
from the beginning that wehad to fly quite
low for the first part of the flight. It is the
reasonwhyweloadedthe balloonwith
four extra bottles of propane.
the mosquito that was on board? Was it
not Swiss-born? Might he not have put it
in a cage, and fed it? Did it have malaria?
PE: Ask Bertrand.
The Cable and Wireless balloon was
trying to get to the Polar jetstream rather
thanflytheSub-Tropicaljetstreambe-
causetheyfeared being dumpedinmid-
Pacific. What didyou think about that?
PE:We alsoconsidered takingthe Polar
jetstreamto cross the Pacific. Three rea-
sonsmade uschoose the southern route.
First, the polar jet stream is oftenassoci-
atedwithprecipitationandturbulence.
Second,thenorthernroutewouldhave
led us to the USA and the northern Atlan-
ticwhereitisimpossibletoflyathigh
altitudebecause oftheheavycivilavia-
tion traffic. Third, the southern route was
possible,withanicejetstreamgetting
readytoblowfromthemiddleofthe
Pacific towards Mexico.
WhenOrbiter arrived atthe Pacific,
were youclear that the flightwould con-
tinue? Wasthis the most critical point of
the voyage?
PE:WhenwecameoutofChina,the
speedwas goodenoughso thatthe deci-
take. The choice between the northern
and the southern route came after the first
third of the crossing. This choice was
critical indeed, but the flight never was
assured. It always needed attention.
The decision totry to pick upa not-
yet-formed Sub-Tropical jetstream south
of Hawaii was gutsy Tellus about it.
PE:The Sub-Tropicaljetstreamwasnot
present at the momentwe tookthe deci-
sion to go there. But all our models showed
itsdevelopmentsouthofHawaiithree
days later. I have to admit that this is a big
successfornumericalweathermodels.
The crewwas not very confident with that
decision. They hadtoflyslowly for two
days and they had to go down to 9 degrees
of latitude.Incredible, isn’t it?
Therestofthetripseemedpretty
straightforward. Were there any problems
on the last half of the flight?
PE:WhenwearrivedoverMexicothe
track was moreto the south than expected.
WeplannedtopassoverYucatanand
Cuba but when we arrived over Honduras
and headed towards Venezuela we had to
stopthatmovement.Thiswassolvedat
thelastminutebyclimbingonly1000
feet. Astonishingly the trackchangedby
25degreesandbroughtusbacktothe
right tracktoAfrica.
Didyouusecomputer modelingby
fillingincurrentdata, and letting it
run?Howfaroutwereyoupredicting
accurately?
PE:Weusedonlythe commonlyavail-
able numerical models from the National
Oceanographicand AtmosphericAdmin-
istration,United States and European Cen-
tre for MediumrangeWeather Forecast,
Reading,UnitedKingdom,withoutfit-
tinginourownwindobservations.In
somecases,likethejetstreamsouthof
Hawaii, the prediction hasbeen accurate
8 to 9daysin advance.
Twenty Days
