[LEAPSECS] aircraft GPS receivers hit by leap second bug

Paul Hirose cfuhb-acdgw at earthlink.net
Tue Jun 11 16:33:44 EDT 2019

[from Flying magazine]

Collins Aerospace notified its user base of a cascade of reports it had 
received beginning at 00:00Z on June 9 that certain GPS and GLU models 
were not operating properly. The specific models, the GPS-4000S sensor 
and the GLU-2100 multi-mode receiver (supporting ADS-B Out 
requirements), are installed in Collins Pro Line 21 and Pro Line Fusion 
avionics systems in many business jets, as well as in some aircraft used 
by regional and major airlines. In fact, Forbes reported on June 9 that 
a slew of airlines had cancelled flights on Sunday because of similar 
issues—including a group of Boeing 717s flown by Hawaiian Airlines.

When we contacted Collins Aerospace on the morning of June 10, we were 
sent the bulletin noted earlier, and advised that operators were 
encouraged to call in with their experience and contact information so 
that they could be informed of a resolution when it had been found. 
Later that day, Collins issued another letter to its user group, 
highlighting the exact problem: “We found that a software design error 
resulted in the system misinterpreting GPS time updates due to a ‘leap 
second’ event, which typically occurs once every 2.5 years within the 
U.S. Government GPS satellite almanac update. Our GPS-4000S-100 version 
software's timing calculations have reacted to this leap second by not 
tracking satellites upon power-up and subsequently failing. The U.S. 
Government distributed a regularly scheduled almanac update with this 
‘leap second’ on 0:00GMT, Sunday, June 9, 2019, and the failures began 
to occur soon after.”

Collins advises operators not to power up units until after the next 
scheduled update by the US government on June 16, 2019, at 00:15Z.

[end quote]


The Avweb site has also picked up the story:

Thinking I had missed a pending leap second, I checked the IERS site, 
but Bulletin C says the offset is still 37 seconds and nothing is 
scheduled. ???

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