The following was contained in an email and sent to AUV Team members. Date: Thu, 12 Dec 2019 10:55:53 -0800 (PST) From: Laughlin Barker To: Hans Thomas , Todd Crawford , Emery Nolasco , Duane Thompson Subject: Summary & analysis of Dec 10-11 I2Map deployment Hi all, Below is a timeline and analysis of the I2Map deployment and recovery as observed and inferred (where reasonable; e.g. start of Transect N based on SBD receipt time of X). Please take time to read through this, and let me know if there are any corrections/questions. Deployment (Dec 10 UTC): 17:25UTC (09:25L): Checkout went smoothly (see attached), and vehicle deployed Vehicle failed to dive after sending mission. HT contacted via phone after repeated re-deployment attempts. ~17:45UTC Discovered that a #define macro present in the mission script hadn't been re-named properly and mission script interpreter was throwing error, killing mission. ~17:50UTC Deployed fixed mission script, vehicle began diving. ~17:55UTC Followed vehicle with USBL for 5 minutes, all appeared nominal, gave bridge go ahead to break away to Midwater 1 for day's ROV work. SBD observations: 21:31UTC (13:31L) Vehicle surfaced after Transect 1, ODSS indicated vehicle was ~5.5km south of desired transect area. Consensus was this was due to strong Southerly current. 22:24UTC (13:24L): SBD (reasonably assumed to indicate beginning Transect 2). 12/11/19 03:12UTC (12/10/19 19:12L):SBD (reasonably assumed to indicate completion of Transect 2). 11 More SBDs, while vehicle performed transitional/relocation transects 09:13UTC (12/11/19 01:13L): Last SBD received during surface interval (Note: This is 2h13m after science requested vehicle begin Transect 3). 13:02UTC (05:02L): SBD received. Reasonable assumption: indicates completion of Transect 3. 13:51UTC (05:51L): Final SBD received prior to recovery. Reasonable assumption: indicates start of (final) Transect 4. Recovery: Based on time of final SBD (05:51L), and an assumed transect time of 4h (Transect 1 dive to first SBD receipt: 3h41m), we would have expected the vehicle to be on the surface and transmitting SBDs by 10:00L 18:15 (10:15L) Arrived on at approximate mid-point of previous nights' SBD indicated surfacing locations. No SBDs received, no RDF signal. Dropped STBD USBL pole, began interrogating for vehicle. Directed boat to steam towards Northern-most extend of SBD indicated surfacings. ~19:00UTC (11:00L) Began receiving USBL hits at ~300m depth. Vehicle was ascending at ~5 m/min. Location: ~5.3km S of deployment. 20:30UTC (12:30L) Vehicle on deck. Mud observed in camera FWD dome baffles, PORT-BOTTOM light bar bent, minor scrapes to PORT-BOTTOM light. No damage observed to acoustic transducers or camera dome. Analysis: Mission script-induced delay: In attempt to make the mission script file more descriptive, the #define timeouts were re-named to NIGHT_TRANSECT3_START and NIGHT_TRANSECT3_START_MINUS_ONE_HOUR (the '3' was not previously present). This change was made appropriately except on line 1967 of the mission script, where the old macro (NIGHT_TRANSECT_START_MINUS_ONE_HOUR) had not been changed accordingly. This resulted in the required pre-processor substitution not taking place prior to shipping the mission to the vehicle over Freewave. This took approximately 25 minutes to diagnose and remedy before the mission was successfully launched at 09:55L. Late start of Transect 3: Based on logfile analysis (abridged version with salient time points below, from HT), the NIGHT_TRANSECT_START_MINUS_ONE_HOUR timeout occurred at 22:24L (24min overdue, attributable to ~24min debug and fix of the above Mission script delay). The vehicle then initiated a sequence of 7 dive segments to setup and return to the desired start point of Transect 3. Of these 7 behaviors, two of them had transit periods of 45 and 28 minutes respectfully. The 45 minute transit behavior ended due to timeout , and the 28 minute transit ended due to completion. The time stackup of all the associated behaviors (standard sequence: gather surface momentum, dive, transit, ascend, get gps, gather surface momentum...), resulted in the cumulative stack-up of ~2h, and thus why the vehicle did not start Transect 3 until 12/11/2019 01:10L Free floating vehicle ascent: The free floating vehicle ascent has been attributed to low altitude lockout (altitude of ~1.4m observed) during the last transect (this is also when the vehicle encountered the bottom). The prop was disabled. The vehicle failed to get a good altitude measurement outside of the the lock-out region. The 24h mission timeout expired, but instead of the vehicle spiraling to the surface in the missionAbort plan, it floated at ~5 m/s because the tail lockout had not been cleared. Attached is a spreadsheet version of the below, and a higher fidelity version examining the behaviors between first occurrence of NIGHT_TRANSECT_START_MINUS_ONE_HOUR and the beginning of Transect 3. Elapsed Mission Time (sec) Elapsed Mission Time (hr) Duration (hr) Time (z) Mission Event 0 0.00 0.00 0951L/1751Z Start first video transect/lights and camera on 11183 3.11 3.11 1257L/2057Z Begin ascend from first video transect 13128 3.65 0.54 1329L/2129Z Ascent complete 16210 4.50 0.86 1420L/2220Z Transit to transect start complete/Start of first lights off & camera off transect. Note - waypoint behaviors in transit timed out (waypoints not reached) 29665 8.24 3.74 1804L/0204Z Begin ascend from second transect (no lights/camera). Extra time due to first several waypoints timing out (waypoints not reached) 31741 8.82 0.58 1839L/0239Z Ascent complete/getGps active 33510 9.31 0.49 1908L/0308Z getGps at end of second transect complete (took extra long) 45299 12.58 3.27 2224L/0624Z Night Transect Minus One Hour reached 50758 14.10 1.52 2355L/0755Z Transit to transect start complete waypoints reached 52641 14.62 0.52 0026/0826Z Night Transect Timeout reached 55289 15.36 2.78 0110L/0910Z Start of third transect/lights and camera on 66853 18.57 3.21 0422L/1222Z Begin ascend from third transect 68874 19.13 0.56 0455L/1255Z Ascent complete/getGps active 71872 19.96 0.83 0545L/1345Z Start of fourth transect. Intermediate waypoints to get to start of transect timed out 86400 24.00 4.04 0951L/1751Z Mission timeout reached 86400 24.00 0.00 0951L/1751Z Prop Turned off due to altitude 95580 26.55 2.55 1224L/2024Z Vehicle on surface mission killed Laughlin Barker Dorado AUV Operations Engineer MBARI 831-775-2079