Wages of Flight
Copyright ©2010 by Paul Niquette. All rights reserved.
On July 2, 1937 at 0000 Greenwich Civil Time (GCT), Amelia Earhart began her take-off roll at Lae, New Guinea for Howland Island 2,556 miles toward the east.  Her specially modified Lockheed Electra 10E, the "flying laboratory" sponsored by Purdue University, took off with 1,100 U.S. gallons of aviation fuel on board, enough for 22 hours aloft at a consumption rate of 50 gph.  Navigator for the flight was Fred Noonan.  His plan called for the plane to fly at an airspeed of 157 mph against a headwind of an estimated 15 mph.  The Electra would thus reach Howland in 18 hours and land with 200 gallons of fuel in reserve.  As known for more than seven decades, things did not work out according to plan.

Waiting for the flight at Howland was USCG Cutter Itasca.  At 1912 GCT, a radio operator on Itasca heard the following transmission from Amelia Earhart (see Simplexity Aloft):
 

KHAQQ CALLING ITASCA WE MUST BE ON YOU BUT CANNOT SEE YOU BUT GAS IS RUNNING LOW UNABLE REACH YOU BY RADIO WE ARE FLYING AT ALTITUDE 1000 FEET.

Many investigators over the years have speculated that the Electra ran out of fuel an hour or more after that transmission.   At 1912 GCT, Amelia Earhart implied that the flight had succeeded in reaching a close proximity to Howland ("WE MUST BE ON YOU").  At that time, there should have been 125 gallons still on board -- enough for two and a half more hours aloft, at the flight's cruise-power setting of 50 gph. Her urgent statement, "GAS IS RUNNING LOW" raises a question: What happened to the rest of the fuel? 

Some 12 hours earlier, at 0718 GCT, Earhart transmitted her one and only position report for the flight (see The Clock Won't Wait).  It included the phrase, "WIND 23 KNOTS," which was higher than originally estimated (26.5 mph vs 15 mph). At the planned airspeed of 157 mph, the stronger headwind would have extended the flight to Howland by more than one and a half hours -- to 1935 GCT.  That appears to be reasonably consistent with the transmission logged in Itasca's radio room at 1912 GCT -- ostensibly from the Electra flying overhead ("WE MUST BE ON YOU").  However, that would require us to make three assumptions... 

{1} That the flight had taken a direct course to Howland, 
{2} That the Electra was indeed in the vicinity of Itasca at 1912 GCT, and...
{3} That the planned airspeed of 157 mph was maintained for the entire 19 hours.
Nota bene, solvers of... Taken together, these three challenges to conventional speculations will lead us to consider the likelihood...
{a} That by 1912 GCT, the flight had already traveled farther than 2,556 miles,
{b} That the Electra was not in the vicinity of Itasca at 1912 GCT, and...
{c} That the overall airspeed enroute was necessarily greater than 157 mph.
Solvers of Which way Amelia? will be given an opportunity to evaluate all three likelihoods and others.  Meanwhile, solvers of Wages of Flight puzzle will find the graph below derived on the solution page.  It can be used to approximate the rate of fuel consumption for any airspeed flown by Amelia Earhart's Lockheed Electra. 

If, as many Amelianna investigators conclude, the Electra suffered fuel exhaustion some unknown amount of time after 2013 GCT, here is one key question...
 

What would be your estimate for overall airspeed 
during Amelia Earhart's last flight?

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