B767-300 and 300 ER
Flight Crew Air Transport Pilot (ATP)
Training / Qualification; Human-Machine Interface
Aircraft Equipment Problem Critical
Aircraft Equipment Problem Dissipated; Flight Crew Diverted; Flight Crew Landed As Precaution; General Declared Emergency
Aircraft; Weather
Just after push back we had to crew defer the right EEC system; which also prohibited us from using the auto-throttle system.  Other than that; we had a somewhat routine departure; climb; and cruise.  As we left our cruising altitude to begin our descent for landing; I believe that we were VMC.  I was flying; but the captain turned on the wing and engine anti-ice himself in anticipation of the moisture below.  Somewhere shortly after we started down; we were IMC and remained this way for most of the remainder of the flight.  Approaching FL240; we got a rudder ratio EICAS message; and the captain's airspeed went down to around 140 knots.  Next; we got an autopilot EICAS message; and I immediately turned off the autopilot and hand flew it for the remainder of the flight.  Maybe a minute later the airspeed on my side became unreliable as well.  We declared an emergency and accomplished the non-normal checklist.  We requested to get vectors to VMC conditions; but there weren't really any large areas of VMC in the area.  The captain asked for the current weather at [the three nearest airports].  The weather at destination was marginal and we were seeing flashes of lightning in that direction.  We discussed our options; and both thought that ZZZ was the best place to land.  The captain requested constant altitude and groundspeed readouts from ATC.  From FL240 to about 14;000 feet; this was the only airspeed I trusted.  At about 14;000 feet it seemed like the standby indicator was beginning to give readings that were consistent with ATC's groundspeed callouts.  Shortly after that; my airspeed indicator became intermittent.  It would temporarily match the standby indicator then go much slower; and then go away completely.  Going through about 5;000 feet my airspeed remained consistent for the remainder of the flight.  I was too focused on hand flying the approach; and keeping my speed to remember what happened to the captain's airspeed indicator.  We got vectors for a long (10-15 mile) straight in ILS and landed with no further incident.This summary is pretty straight forward; but this was an extremely stressful event.  The combination of flying IMC; at night; with no reliable airspeed indicator; no auto-throttles; and being in an aircraft with fuel flow in Kilograms; while relying on a procedure that says 'maintain pitch and power setting for phase of flight'; made this a very uncomfortable flight.  I think the captain and I worked very well together to create the safest outcome.  The captain's communication with ATC was instrumental as well.
After push back and subsequent start of the right engine; we received a RT EEC MODE EICAS message. The left engine was started next; following with a flight crew deferral. Contact to flight control was made; an entry made into the log book; and outlined deferral procedures followed. One result was the loss of the auto-throttles. Subsequent climb and cruise were non-eventful. FL 330 altitude; later to FL 350.We received a descent clearance and were proceeding direct to the airport. At altitude we were VMC on top with lightning ahead of us to the east. Shortly after initiating the descent; I turned on the engine and wing anti-ice; as we were IMC with light precip; some St. Elmos fire; and cloud to cloud lightning. This was descending through FL300-FL280. Radar indicated moderate CB's to our south; tracking northeast.At  FL280 I noticed an ELEV FEEL status message. Shortly thereafter; the F/O indicated that our airspeed indications were trending away from each other. The standby air speed indicator was at Zero. Rudder Ratio illuminated; followed by A/P Disconnect with aural warnings; A/S Unreliable- amongst others that I don't recall and I'm not sure of the exact sequence either. As I was starting to digest what we had; the F/O indicated that his a/s indicator was failing. I told him to level off @ FL250 and set a power setting that he felt would give us level flight. I declared an emergency and referred to the QRH to comply with the Airspeed Unreliable EICAS message as it had priority. I read off the items and info's of other systems that may be hampered.After this; I requested current wx and zeroed in on destination at 1000 and 1 mile; with ZZZ at 3000 and 5 miles. Destination ATIS also indicated LLWS alerts in effect. With the CB's to our south tracking towards the airport and our position fairly equidistant; I chose to divert to ZZZ and notified ATC.It took us awhile to execute a 180 turn because we limited our bank angle to 5 degrees. I requested altitude and groundspeed inputs from center; with a request to inform us of 20% deviations from what appeared normal to them. Prior to the turn; center indicated we were 540 knots across the ground. This appeared to jive with the EADI GS and wind readouts (240 degrees at 140 kts). At completion of the turn; I requested another readout. I recall center indicating it was still over 500 kts. EADI GS and direction were now from the south east at 140 knots. This was very confusing and unsettling and led me to be suspect of other instrument readings. At no time did we receive either an overspeed warning or a stick shaker. Our rate of descent increased in the turn; but not alarmingly so. The F/O was handling the aircraft well; so I concentrated on managing the event so as to not get fixated on any one item. Heading towards ZZZ; we had no a/s indications of any kind. I believe we leveled off for a short while at FL180. At this point; the F/O's a/s indicator started to come to life. I revisited the QRH and selected 'ALT' on my ADC switch; as directed. This brought my a/s to equal the F/O's at  280 kts. However; this did not last and after about 5 seconds both a/s dropped to unreliable values (Less than 100 knots as I recall.) I deselected ALT with no change in indications. I also deselected the strobes and delayed the landinglights until later to help mitigate spatial disorientation.At this point I began to shift my focus to the approach checklist. I briefed the ILS and built it in the FMS; and we were now in the terminal area on downwind. I requested a 20 mile final. Abeam the outer marker the F/O indicated his a/s was coming alive. We configured the flap settings for landing based on his indicator. On base; the standby a/s came alive to match the F/O's. Upon G/S intercept my a/s appeared normal and the landing was without incident. CFR met us on the ramp and told us that the exterior of the jet showed normal. The entire time we were IMC; until the turn to base.The QRH directs the crew to a pitch and power setting table for various altitudes for this situation. The print is so small and faded that even in the best of conditions it is difficult to read. Turning on the overhead lights to get a better look; even momentarily; is stupid. ATC assistance was invaluable.
B767 flight crew describes a decent and diversion in night IMC with all three airspeed indicators inoperative. All three indicators return to normal during approach.