Tuesday, March 1, 2011
Flying A BOAC 707-420 To Seattle And Back, Great Polar Navigation Segment.
From Flight Global Magazine 25, November 1960
Another great article on flying a BOAC 707-420
ONE lesson I learned from a recent double crossing of the
Atlantic and the US is that pure navigation and cruise
control are increasingly subordinated to traffic control,
in respect of both tracks and heights. The aids are relatively poor
and old-fashioned, though they work well in good conditions,
and the competition for the best height or track is so fierce that
it takes a cunning captain to operate his aircraft as the designers
intended. He needs something of the craftiness and skill of the
old tea clipper captains.
For me it all started rather suddenly when I managed to join
a BOAC Boeing 707 proving flight via New York to Hong Kong,
drop off at San Francisco, fly in a United Boeing 720 to Seattle
and come home non-stop past the Pole on BOAC's 13th 707-420.
An Atlantic crossing consists of an airways departure and arrival
bracketing a classically navigated over-water flight. ATC separations,
based on expected navigation accuracy, require 120 miles
lateral, 30min longitudinal and 2,000ft vertical separations between
airliners. You fly even flight-levels to Shannon, odds westwards
over the water (evens eastwards) and the best height available into
New York. The shortest distance is the Great Circle, but you
may plot a rhumb line to the south or a Polar curve to the north,
mainly to take you through more favorable winds circulating
round lows or highs. Jet airliners do not fly classical pressure
patterns, but the three routes allow a degree of pressure flying.
BOAC deviate from the Great Circle only if they can forecast a
rime gain of better than 15min. Because of ATC limitations, the
cruise technique for the 707 is to fly at near M0.81 at about 93 per
cent r.p.m. and at constant height, hoping for the best height but
having to accept what ATC allows. As the aircraft gets lighter,
speed increases and at M0.82 r.p.m. are reduced to drop speed
back to M0.81. This process is repeated as required.
The flight-planned track is made out for successive beacons
and then for "lat and long" positions, reporting every 10" of
longitude by HF/RT to the appropriate centre—Prestwick,
Reykjavik or Gander. The navigator makes a DR plot on a
1:6,250,000 chart overprinted with Loran lattices and Consol
count lines as well as the main beacons. He can use Loran and
Consol, astro, weather radar, NDBs on weather ships or at other
—often surprisingly remote—locations.
Weather Station Ships Bravo And Charlie location
Bravo 50*30"/ 51* Charlie 52* 45"/ 35* 30"
Weather Ship Type
We took off from London weighing 134,600kg with a 42sec
ground run, planning Green One to Shannon and thence by Polar
Curve at 33,000ft north of weather ships Charlie and Juliet, south
of Bravo and to Goose. This avoided some rather aggressive
lows. After Goose we joined the air routes and plunged into the
New York maelstrom. I tend to doff my hat respectfully when
people mention New York now. We estimated 535 m.p.h. in
ISA + 8°C, a 7hr flight leaving Ireland at 13.20Z (GMT), midwater
at 1500Z, Goose at 1705 and passing Montreal at 1840.
England and Ireland slipped away in the rock-steady rumble of
the 707. Over the water, high-level sheets and veils of cloud
scissored in perspective over mattresses of thicker stuff lower
down. There was the odd cloud street or ridge and I had the
impression of an underwater landscape floodlit.
The 707 is intended to be flown under autopilot control (Bendix
PB-20) between take-off and landing. The pilots are no less busy
In the heading picture is a BOAC Boeing 707, the type in which most
of the journey here described was made. It is a powerful and efficient
aeroplane, greatly liked by its crews.
when the autopilot is engaged than the driver of a car with an
Flight level 370 was taken by the military on this day (it often
is) and the temperatures were too high to allow us to get through
to 390, even if ATC cleared it, so we stayed at 330. You would
think that every jet airliner tried for one ideal track at the same
time, but ATC get over this by designating Lundy, South Shannon,
Bush Mills and Prestwick as starting points for the track,
with equivalent points on the other side. You could also plot a
composite track, usually made up of two legs each of one of the
three basic types. BOAC have the Edo Loran and, with the
aerial high up in the new fin k gives good results unless the
northern lights or static play it up.
The trick is to arrive at the Canadian Air Defence Identification
Zone reporting point within 10 miles laterally or 5min
longitudinally. Otherwise they file a violation, which means real
trouble. A plain Loran fix can be obtained in 2min and a fix
compensated for aircraft progress in 3min to an accuracy of two
or three miles in good conditions. In bad, it may be 20 miles.
The CADIZ entry is usually made from a series of fixes along
a run-up track to a point about 150 miles from the Canadian
coast. VOR can come in at about 200 miles and weather radar
will identify a landfall at about 100 miles. Where accuracy
is important, the aids seem to be reasonably abundant.
At 1630 we were approaching land, radar showed a faint blur
at 100 miles and VOR was beginning to come in. By 1650 we were
talking to Goose on VHF, the radar was off and we were getting
the air route clearance into New York. The home stretch was
starting. The instruments showed M0.82 with 88 per cent r.p.m.,
we had been cleared to flight level 350 with — 52°C and could
now have made the step to 390.
By 1735 we are over the lake-pitted Canadian wilds and have
the wide St Lawrence in view far on our left through breaking
sheet cloud. We are past Goose and climbing an ADF ladder
past Lake Eon and Seven Islands NDBs, along the St Lawrence
to Mont Joli and Montmorency NDBs at Quebec. We are getting
airways clearances and things are warming up, with a good deal
of radio tuning and consultation of charts and manuals. At 1830
we have been flying for 6hr 4min. We are cleared along the high
level Jet 75 Victor across Plattsburg VOR to Albany VOR. Here
we descend from 350 into Victor 91 at 250. All this has been
received and written down by the co-pilot. The let-down involves
throttling the outboard engines to 50 per cent and the inners to
68 per cent, the engineer working throttles and cabin pressure
controls together to avoid "bumps." Descent is at 290kt and
2,500ft/min. We have radar advisory service, but they lose
contact briefly about here. Capt Nisbet, 707 Fleet manager, has
now disengaged the autopilot and is flying manually.
Then it comes thick and fast with successive hold height and
descend instructions. Albany VOR to Poughkeepsie range to
Wilton VOR, to Syosset (intersection of Idlewild and Wilton
radials), to Hempstead range, out along its south-west leg to
Lido NDB and round to Ambrose (intersection of Idlewild and
Colts Neck .radials); and all the time stepping down in height,
reading checks, tuning radios, reading charts and using VHF to
receive and check instructions and be told by radar of lots of
other traffic. The clearance is somewhat changed as we progress.
We pass Wilton at 15,000ft, Hempstead and Lido at 8,000.
Ambrose at 3,000 and put down 20° and then 30° flap and gear
and slow up to 180kt. Cleared to ILS for Idlewild 04 runway
a: 1,000ft, cleared to circle round left-handed for our designated
landing on 31R and finally down with a roar of reverse thrust.
Landing weight, 88,000 kg; cross the hedge at between 130 and
;40kt. A fine piece of hand-flying and snappy team-work—and
the distance from Wilton to touchdown is probably less than 60
We made the New York to San Francisco crossing next day
in 5.45hr. Take-off 42sec at 136,600kg gross, cruising at 31,000ft
on air routes all the way. The writer shamefully asleep in a reclining
first-class seat. "Frisco" to Seattle was made next morning by
United Boeing 720. Take-off weight, 187,0001b (United use
pounds); ground-run 32sec; VR 122kt; V2 137kt is reached at
35ft. A Convairliner landed parallel 200yd away as we took off.
We cruised at M0.83 at 28,000ft; estimated flight time l^hr.
Loitered round Mount Rainier (14,000ft plus) at 28,000ft while
fog lifted from Seattle Tacoma. Emerged from cloud close to
the top of a crane jib and made perfect landing. The 720 is as
fine an airliner as the 707.
Home Past the Pole
The flight home was in the thirteenth of BOACs Boeing 707s,
non-stop over Canada, Hudson's Bay, Baffin Island, Greenland,
past Iceland and over Northern Ireland—airways to Carmi, just
inside Canada, direct to Frobisher, great circle to Bush Mills and
airways to London. The crew: Capt "Dexter" Field (who did
much of the acceptance flying on this and previous 707s), 1st Offr
Jack Butt and 1st Offr John "Skate" Lee as co-pilots, Nav Offr
"Danny" Kaye, Engr Offr D. Donaldson, Engr Offr H. Breslin,
and Ch Stwrd S. W. Hemming. The last named was required even
on this ferry flight for certain emergency drills, but also acted as
a most welcome supplier of tea, coffee, food, etc.
Our take-off weight was 130,500kg, of which 72,000kg represented
full tanks. We needed, with all allowances, 66,500kg of
fuel for the 4,210 n.m. flight. Estimated flight time 8hr 42min on
a minimum-time track, with average +24kt wind component,
calculated by BOAC's New York dispatching office and received
in Seattle by telephone. The 72,000kg of fuel would giye us
llhr 48min endurance. Track: Carmi, Churchill, Frobisher,
64°N at 50°W, 56°N at 10°W, Bush Mills, London. Flight level
330 to 90°W, 370 to 20°W, then 410. Take-off about 1700hr local,
Take-off clearance: "Climb on runway heading to 3,000ft:
left turn to heading 340° to intercept 030° radial of Seattle VOR:
climb NE-bound until 15,000ft via direct Carmi: maintain flight
level 330. Transition height, 24,500ft because of the mountains.
Gets dark during climb, red rotating beacons reflecting off pods;
flight deck almost Christmas-like in red and white lights on grey
panels: everyone head-down working hard, except pilots peering
into night sky. We press on to cruising height, mostly using DR
plot and scattered NDBs with occasional VOR.
Talking to all sorts of stations on VHF and HF, asking for
position reports to be passed to BOAC at Montreal. Distinctly
Canadian accents on radio.
Change heading from 025° to 060°. Meet jarring turbulence:
navigator's plot shows sharp wind-change: radar shows thunderstorms:
temperature drops rapidly; lights dimmed and captain
stares into black night, hand on autopilot heading control. This
is a jet stream—and rough! Decide to climb straight to 370 to
get clear, and notify control. Using both VHF and HF almost
constantly. Pass Tippo Lake at 0202Z estimating Churchill at
0300Z. Dull, furtive veils of northern lights snaking above us—
plays hell with the radios. See ice or snow through gap in clouds.
0230Z: Sextant aperture frozen tight, so no astro. Not in Loran
cover yet and probably blacked out when we get there. We are
told that Churchill is due to launch some rocket at our exact ETA
overhead! Search manuals, find their HF frequency, ask them to
desist, but fortunately the firing is delayed anyway.
O315Z: Past Churchill at 37,000ft, M0.82, ETA Frobisher
0435Z. Lqran switched on but not performing yet. Magnetic
variation nil at Churchill, but builds up at l°/min to 54° in the
700 miles to Frobisher. Using Polar Path gyro on DG. 0337Z:
Just getting one Loran line over Hudson's Bay. 0430Z: 480kt
TAS, heading 030°. Weather radar mapping, Loran on, both
ADFs tuned to Frobisher NDB, no astro. Outside air temperature—
52°C. Hear SAS over-the-Pole flight asking to climb from
280 to 310 at 0449Z, position 70 °W, 66 °N. KLM flight is there
too. Northern lights seem to have gone. We talk to "Leeway" on
VHF. 0445Z: Note from co-pilot Lee, "Leeway is defence radar
at Frobisher: we saw their lights on the ground: have now
returned to compass steering: will get radar fix on No 2 VHF
at about 0455Z: now reporting to Goose on No 1 HF." Our
report, read from a form, gives estimate for 64°N, 67°W as 0509Z,
the wind found, fuel state and consumption, spaed, ETA for
London and much besides. Goose asked to repeat to Gandar and
Montreal for BOAC, to Sondrestrom for ATC. Sondrestrom
cannot understand, so Goose changes HF frequency to try again.
"Leewey" fixes us by radar at 120 miles. SAS and two other BOAC
aircraft talking on HF. Navigator plotting all the time; engineer
fills in fuel tables every 5,000kg, about every 40min. Pressurizing
on one turbocompressor and two direct engine bleeds. We call
Prestwick on HF, apparently without reply.
O53OZ: Northern fights sneak up again. ADF tuned to Kook
Island NDB, mid-west of Greenland, and we see its lights below.
Whoever lives there? No 2 ADF getting Christiansund NDB,
320 miles away on southern tip of Greenland. At 37,000ft: TAS
475kt; two minutes up on ETA; winds northerly; engines at 88
per cent r.p.m.; radar tilted down 7° for mapping.
0542Z: Temperature — 55°C. Air has been smooth for hours.
Captain and navigator still hard at it, co-pilots and engineer
relieved. Passenger cabin a dark, empty tunnel—only nine seats
fitted. Dead of night, northern lights stealing about.
O625Z: At 35°W and 37,000ft. Hope to climb at 30"W. Three
min ahead of plan. No VHF contacts. Iceland cannot hear our
HF, so relaying via Sondrestrom. Expect to contact weather ship
on VHF at 0645 and get fix. Nearest to Iceland at 0700. Many
other aircraft south of us calling Gander. Receive HF weather
broadcast from Shannon giving shallow fog for most British airfields;
also Canadian maritime weather broadcast from Gander.
Frobisher has a 9,000ft runway good for a diversion. Our point of
no return relates to Gander. But now we have the feel of the other
side and are heading south-east for Britain.
0800Z: Wake with a start from sleep to see a hard yellow,
copper and pale green dawn rising over us. Still making 480kt
true on 132°. ATC has held us down to 37,000ft; passing 10°W
and estimating Bush Mills at 0830Z. Windscreen frames now
thickly coated with frost. The sun begins to shine dazzlingly
straight in at the windscreen, and shades are down, lights turned
low. Outside temperature — 48 °C. Captain still in seat.
Navigator makes complete table of airways check-point ETAs
for Red 1 and Amber 1 via Belfast, Isle of Man, Wallasey, Lichfield,
Daventry, Beacon Hill and Watford to LAP's runway 28R.
according to Boeing, be unusable for structure in contact with the
airstream at speeds above about M2.1. Another argument against
M3 is that this speed will save only 40min over an M2 flight from
New York to London.
Cruising at M2, one supersonic airliner carrying the same payload
as a 707 will have a block speed of 900kt—about twice as fast
as a 707—and will do 15 per cent more flying hours. It will be
attractive on sample PanArn routes because it will "fit the clock"
and allow really convenient scheduling.
Boeing have naturally considered the economics of the supersonic
airliner and state that these can be realistically reckoned at
about 15 per cent above those of the 707. One estimate even makes
the costs the same.
The range quoted above is .intended to make the airliner capable
of flying from the eastern seaboard of the US to centres well inside
Europe non-stop—Copenhagen, Frankfurt or Rome for example—
regardless of winds. There is a range and speed economic limit
beyond which size becomes unprofitable for a given payload.
The aircraft will cruise supersonically only over sea and would
make a small part of its journey at subsonic speed over land, for
example, across France to Rome after crossing from New York.
The problem of shock-wave trailing over a 50-mile-wide swath
of countryside is intractable, as has already been realized from
supersonic flights made by military aircraft. The progress of a
B-58 making a supersonic test penetration of Norad area to
Milwaukee could be clearly tracked by the swamping of successive
telephone switchboards by callers notifying all manner of strange
and improbable disasters. One of the main public relations problems
is to make people recognize a sonic boom so that they won't
think that something—their central heating boiler in US society
—has blown up.
A low-level supersonic pass is definitely destructive. A B-58
pass at M2 at about 40,000ft is extremely noisy but little more.
A boom is double because of the initial pressure rise and subsequent
recompression of the air, spaced about 0.5 sec apart. Pressure
rises up to llb/sq ft on the ground are disturbing and often
mistakenly identified as accidents, but do not cause damage.
Between 1 and 31b/sq ft is objectionable. Boom intensity is
partly according to the volume of the aircraft and partly according
to the lift being generated. The second factor has not hitherto
been important, but will now make a major contribution in supersonic
airliners because L/Ds of 7 and 8 or even 10 are being
sought. These could by themselves cause a 21b/sq ft pressure rise
in the boom at ground level.
On one occasion the pressure rise was actually measured as a
boom struck two plate glass windows, each measuring 5ft by 10ft.
One window cracked across with a rise of 1.751b/sq ft. The other
remained intact. The boom will not affect ships because their
structure and windows are much stronger, but the disturbance to
people will remain a problem. Pressure rises between 2 and
2^1b/sq ft will not damage the ears.
Two factors are considered definite by Boeing. The airlines
cannot afford to be liable to damage claims from supersonic flying;
and neither can they tolerate having to operate in specific corridors.
Supersonic booms may be felt 25 miles either side of the aircraft's
track and wind can alter the distribution, but the higher pressure
rises will occur only over a 10 mile-wide band.
Finally, Boeing appear to be a little sceptical about the possibility
of co-operating with European companies in designing^ a
supersonic airliner, mainly because of the obvious commercial
implications. But they feel that all the problems can be solved
and think a suitable communications system for effective technical
liaison could be developed. They insist that design leadership
would have to be firmly vested in one company.
\Descent to begin at 0852 and to last 24 min at mean TAS of
364kt, using 800kg fuel. Engineers plan pressurization management
between bleeds and turbos when throttled back on descent.
ETA London 0916Z with 19,000kg of fuel remaining at 1,000ft.
The tip of Ireland is painting well on radar at 60 miles. Sun is
blinding. A leaden sea visible between dollops of cloud thrown
almost up to our level in polar maritime cold air. IAS 250kt;
M0.82; r.p.m. 88 per cent; o.a.t. — 48 °C; cabin height 6,000ft.
Navigator hands time plot to co-pilot and relaxes slightly. HF
weather reports in French. Cillard RAF radar (in Scotland?) has
us. English voices, clipped and calm in welcoming efficiency.
082OZ: Ireland in sight. Centre and reserve tanks now dry,
remaining fuel distributed in wings. 0837Z: Cillard loses us and
we switch to Scottish Airways control. Estimate Isle of Man at
0843. Prepare-for-descent checks read out. Landing weight will
be 77,500kg—very light—VREF 126kt, target threshold speed
135kt, maximum threshold speed 149kt.
0842Z : Pass Isle of Man, in sight below, together with coasts of
Wales, Ireland, England and Scotland, and request descent clearance
for 0851. At 0846 cleared down to flight level 210 and call
Preston. Throttle outers to 68 per cent and inners to 87 per cent
r.p.m. Descending at M.O.68 at 700ft./min. Wallasey at 0853.
0900Z: The Pennines lava-like in valley fog and snowy tops.
Joddrell Bank telescope like a deployed parachute far below.
Atlantic charts and manuals being cleared away. Pass Lichfield,
estimating Daventry at 0907, tuning beacons, change to London
control. 250kt i.a.s., jolted in rough air. Daventry at 0907, estimating
Beacon Hill at 0913. Cleared to flight level 190. Watford on
No 1 ADF, Dunsfold on No 2 ADF. Find Beacon Hill by Flying
Dunsfold range leg to a bearing from Watford. Under London
radar surveillance from Daventry. Cleared to flight level 080.
Don't confuse Beacon Hill with Woburn, check with ADF.
l,000ft/min now at 150. Wheels rumble down for airbrake effect,
slow to 200kt at 2,50Oft/min; trying to make Watford at 8,000ft.
Over Watford at 11,000ft radar takes us straight on to a
southerly lead-in for ILS, asks our rate of descent. Runway visibility
1,500yd. Still on autopilot, in cloud. Flap coming down. See
Greenwich through a hole in cloud, then Crystal Palace. A helicopter
is reported leaving Battersea. Approach checks read. Autopilot-
coupled glide-path and localizer armed. Radar vectors us on
to centre-line. Speed coming back to 150kt at 3,200ft. QNH set
on co-pilot's altimeter, QFE on captain's. Height 2,100ft, glidepath
coupler engaged at 152kt, going down at 900ft/min into dull
mist. Melted frost dripping fast from window frames. Captain's
hand poised on control wheel. Windscreen wipers working hard.
Lead-in lights now dimly in view, but no trace of runway.
BEA engineering base comes into sight to our left, co-pilot
postively identifies runway and tells captain. We surge in past the
lights, the captain cuts the autopilot and holds off. When I think
we are still 100ft up, the main wheels touch smoothly, the nose
comes down, spoilers are popped out, reverse thrust pulled.
Further end of runway still out of sight. The captain takes the
nosewheel tiller and starts braking while the co-pilot holds the
column forward and calls the decreasing speeds down to 60kt. We
turn off with some runway to spare, switch to airfield control
frequency. Shutting down checks begin. We are home.
Chock-to-chock time 9hr 15min for 4,210 n.m.: we took off at
about 1700 hr Seattle time and it is now 0130 by that reckoning—
time for bed. But here in London it is 0900hr or so and a new day
is just beginning. This is the way to travel if you don't weaken. ..