DOCUMENTATIONWarnings and Alerts
The aircraft alerts you in two places: the warning lamp panel in front of you, and - on the U-2S - the alert line at the bottom of every MFD. Both feed the Master Caution.
Master Caution
The MASTER CAUTION lamp lights for every new warning or caution (not for advisories). Press the lamp itself to reset it - that also silences the tone, which sounds at once for a warning and 5 seconds later for a caution (MASTER VOL at its stop mutes it, as it mutes all headset audio).
The EFB Settings tab option Master caution tone mutes this tone for good; the lamp still lights. The individual lamp or message stays until the problem is gone.
- An alert you inhibit on STAT → HIST no longer lights the master caution - neither from the MFD nor through its warning panel lamp.
- Engine start: on the ground, a repeat of SEC below 55 % N2 or of AMAD below 48 % N2 does not light it again. The first one still does.
- The INBD 30 and OUTBD 150 fuel lamps light without the master caution unless a fuel dump is selected.
Alert Levels on the MFD
| Level | Color | Meaning |
|---|---|---|
| Warning | RED | Act now. |
| Caution | YELLOW | Act soon. |
| Advisory | CYAN | For your information. |
L7 ACK acknowledges the newest alert. STAT → ICAW lists everything that is active, and on STAT → HIST you can inhibit nuisance alerts so they no longer light the Master Caution - see Status Pages.
Warning Panel Lamps
| Lamp | Comes on when... |
|---|---|
| FIRE / OVERHEAT | Engine fire / overheat, or the FIRE/OHEAT TEST switch |
| DC GEN | DC generator not on line (normal before engine start) |
| MAIN AC | Main AC generator not on line (normal before engine start and on external power) |
| ESS AC / EMER AC | That AC bus has no power |
| MON DC | Monitored DC bus at 25 V or less (or dead) for 15 seconds; out as soon as it is back above 25 V. The MFD message MON DC VOLTS LOW uses 25.5 V and goes out at 27 V |
| UTIL BATT LOW | The utility battery at half charge (24 V) or less |
| SHED | In the ESS DC SHED button on the main panel, right of the instruments: pressed, the secondary essential DC loads are off (see Battery only); press again to restore. It lights the master caution while shed. Every flight starts unshed |
| EMER BATT ON | In flight only: the utility battery has run down to 10 % (about 21 V) and the emergency battery has taken over. Stays on until BATTERY is held OFF for 5 seconds |
| HYD | Hydraulic pressure below 2,500 psi |
| SPOILERS | Spoiler emergency accumulator pressure low |
| OIL | Oil pressure below 10 psi |
| AMAD | AMAD oil temperature 200 °F or more, or AMAD oil pressure low (it goes out near idle on the start) - normal with the engine stopped |
| FUEL SUMP | Sump tank at 38 gal or less |
| OXY | An oxygen system is off, low on pressure, or below 1 liter |
| GEAR | Gear up with flaps 20° or more, or on the ground |
| H-70 LEAK | The emergency start system has been fired (hydrazine used); serviced when parked with the engine off |
| INBD 30 L/R · OUTBD 150 L/R | That tank has reached its fuel-dump level |
| XFER PRESS LOW | A cross-transfer is on but nothing is flowing, or a sump-tank transfer is filling a low sump |
| AIRSPEED | 180 KIAS or more (230 with gust control up) |
| AUTOPILOT | AFCS powered with an axis switched off or tripped |
| CONFIG | Gust-control surfaces not where the switch says (e.g. no hydraulic pressure) |
| SEC | Engine in secondary control: ENG MODE in SEC, an automatic transfer, or the engine stopped or still below 54 % N2 in a start |
| IFF | Transponder off, or Mode 4 on with no code to reply with |
| AUTO TRIM | Autopilot auto trim failed (AFCS powered, PITCH TRIM MODE in AUTO) |
| BCDU | BCDU fault |
| TR OHEAT | Transformer-rectifier overheat |
| BLEED | Bleed air leak, or the FIRE TEST position |
| EW REC · EW RPT | Beside the SFD. REC: the EW system (EW CONT in REC or RPT, self-test done) is tracking a threat - in our rendition sim traffic within 5 NM and 1,000 ft, moving faster than 20 kt. RPT flashes while the system is jamming it in RPT; REC is always on when RPT is. |
Lamp test: hold MASTER LIGHT TEST (the AOA indexer, the AFCS lamps, EW REC / RPT and the red gear handle light too, the MFDs show LANDING GEAR NOT DN, and the LOX needles run down towards zero, which brings both oxygen warnings after about 9 seconds; held for more than 7 seconds it also gives FLAP GUST MISMATCH and AIL GUST MISMATCH).
Fire detection test: move the FIRE/OHEAT TEST switch each way, then back to center - FIRE TEST gives FIRE and BLEED AIR LEAK, O'HEAT TEST gives OVERHEAT.
MFD Alerts
Each MFD message, with when it comes on, when it goes away and what to do, is in the ICAW Message Dictionary.