MEDUSA

No MEDUSA flasks.  Flasks in Costa Rica were held up in customs.

AO2

WT is low-420, so attempting to conserve gas during preflight.  
15:45ish: Forced second cal to avoid jet fumes
16:42 Attempted to force back to AUTO/40 min Cal Interval but cal wants to start immediately, so kept in Manual for now
16:55ish Transition from rainforest to Gulf of Mexico at 16N, Honduras coast.
16:04 Sudden +10 per meg in O2 corresponds fairly closely to start of purge for LS, though sign is wrong for LS to be somehow leaking through.  No other tracers (CO O3 BC CO2) seem to reflect a feature of interest.  This higher value continues after the cal.
17:45:20 Stopped HS purge to get data for drop to 28kft
17:46:18 Started descent to 28kft
18:33 to 18:40 PCAB climbs quite steeply to equalize at 1000 ft level.
18:38 Large Oil Tanker seen off right of aircraft.  May be contributing to 80 pm dO2, 
18:42 Second large oil tanker seen of right of aircraft.  Well... It is the Gulf of Mexico. This one coming toward us, less likely to be influencing measurements.
19:00 Switched to AUTO, but then ozone peakedand O2 started dropping more, so returned to MAN at 19:02.  
19:04 Returned to AUTO. LS Purging.
19;04 Back over American Soil... And in Cal, so missing some of signal. 
19:07:20 LS starts
19:08 Wander in cals in very noticeable at this point, with a wander in the LS of 
19:10-> A large amount of biomass burning going on.  BC doesn't respond, since we are at 43kft and wind is coming from (East?) at that height.
20:02:10 Starting descent into Ponca City--Missed Approach.
20:08? Maintaining 200.
20:21ish Starting cal
20:29 told to lower to 160
20:35 Dropping more rapidly to PNC.  
20:36:40 light chop
20:37:35 Medium chop
20:43:45 PCAB ascends rapidly at Boulder height over PNC.
21:22 Contrail visible close off the right wing-possible signature?
21:32 Forced Cal while holding at 320.  
21:33 N677F told to descend and hold 300.
21:43 Just as cal ends, we are cleared to level 270.