Minimums, Minimums
In the midwest where I normally fly, its pretty rare to have an airport socked in by fog. It happens on occasion, but usually burns off by mid morning. A few weeks ago was the exception to the rule. DTW fogged in around 6am and stayed that way most of the day. In one flight we logged 2 CAT II approaches, one to bare minimums, a missed approach, holding, a near diversion and a low visibility taxi. I have not flown in such foggy weather like this since my freight hauling days.
It all started out with a 4:45am wake up call. This was to be day 2 of a 4 day trip with 2 easy legs. We were going from AVP-DTW-OMA for a 20 hour layover. Everything was very routine and normal until I started my walk around and took a look at the fuel panel. As part of my walk around, I normally open up the fuel control access panel and turn the panel on. This way I can see how much fuel has been loaded on the plane. It struck me as very odd that we were loaded up with nearly 9,000lbs of fuel for a 1:15 minute flight. Typically we wouldnt take much more than 6,000lbs. So I immeadiatly figured we had an alternate. I finished up the walk around after a few minute delay in the -200 F.O slice of heaven and headed up to the cockpit. As I was taking my jacket off and stowing it, the Captain turned around and said "This is going to be an interesting morning" and handed me the flight release. I took a look at the weather in DTW and saw exactly why we had 9,000lbs of fuel, DTW was forcasting light winds, 1/2mi visibilities with fog and a 100ft ceiling. Temporarily from about an hour before we arrived to 2 hours after our arrival time the forecast dropped to 1/4mi visibility and fog. Since the visibility forecasted was less than the published minimums of 1/2mi vis, we needed to add 2 alternate airports and enough fuel to fly to the farthest alternate plus 45min of reserve fuel. Hence the 9,000lbs of fuel on board.
The self loading freight boarded up and we shut the door and pushed back. We were expecting a flow control delay into DTW on the taxi out, but it never came. We lifted off a few minutes later into a black, starless early morning sky. Since it was my leg, during the preflight briefing, I infomed the Captain that I would be flying at long range cruise to conserve fuel. As the airplane leveled off at our cruising altitude of 28,000 ft, I pulled the thrust levers back and set LRC power to bring our fuel flows from around 1250lbs per hour to around 1000lbs. This 500lb reduction in fuel flow would come in handy in about 45 min.
As fast as airplanes are, they are not fast enough to outrun the sunrise. Enroute to DTW, the sun was making its way over the horizon. Thankfully the sun was behind us, because its much easier on the eyes at O'Dark thirty. But with the sunrise comes the fog. We were monitoring the ATIS through our automatic acars updates and in the span of about 20 min, we went from atis L to R. That means the weather at the airport changed 6 times in a very short period of time. The visibilities were fluctuating between 2200 rvr and 800 rvr depending on runway. Pretty soon we get the call from ATC telling everyone that DTW is only accepting Cat II and III aircraft. Thankfully both the aircraft and the crew (us) were Cat II certified. This means that we use a little different technique and procedures to land when the visibilities are less than the standard 1/2 mile vis or 2400 rvr. We are allowed to land with an rvr of 12ooft. For those of you wondering what RVR is, that stands for runway visual range. Since we were able to do a Cat II approach, we continued to DTW while those who were not able to shoot the approach were given holding instructions.
The closer we got to DTW, we could see what the problem was. We could see the buildings of downtown Detroit sticking through the thick layer of fog. Closer to downtown, it was a thin low laying layer of fog and clouds. The closer to the airport you looked, the thicker and more dense the clouds/fog got. As we were on downwind for 3R, we heard an aircraft or two get cleared for the approach. Then as we were about to turn base, the approach controller stated the rvr had dropped to 800ft. This is lower than what we are authorized for therefore we could not commence with the approach. Neither could the other 3 or 4 aircraft in the pattern at that time. Since we were so close to the airport and off any published airways, the approach controller put us into a radar vectored holding pattern near the outer marker. At this point its all asses and elbows in the cockpit because we are very busy flying the aircraft, checking our fuel state, checking weather at our alternates, talking to dispatch and trying to make PA announcements to the passengers to try and keep them in the loop. Granted we had been doing most of these things enroute and had come up with a gameplan in case we couldnt make it in to DTW, but now we needed to start planning on putting it into action in case we infringed on our bingo fuel. We came up with a bingo fuel number a little earlier in the flight. Bingo fuel for us that morning was enough fuel to get from DTW to our alternate, shoot an approach and still land with 2100lbs of gas in the wings. In midstream of getting all this done, approach announced the rvr on 3R had gone back up to 1200ft. So we momentarily stashed the plans and preperations to divert and re-prepared for the approach. We were vectored on to 12 mile final behind company traffic and cleared for the approach. The aircraft in front of us was switched to tower frequncy and shortly thereafter we were as well. It was about this time when the weather decided to throw another wrench into the morning. The aircraft in front of us contacted tower and informed them that they were inside the final approach fix on the ILS approach to 3R. Tower then cleared them to land and informed them the rvr was back down to 800ft. For them, its not too big of a deal because they are still legal to continue the approach and continue to the Decision Height and can "take a look", for us, it creates more of a problem because we cannot legally continue the approach. We were outside the final approach fix, therefore could not continue the approach. By the time we got a word in with tower, we had already proceded past the final approach fix and were heading down the ILS. Tower cleared us to land, but we couldnt, so we informed him that we would have to go around. A few seconds later tower issued missed approach instructions and I poured on the coals and performed a go around manuver. While we were in the process of the go around, we were handed back off to approach. The controller informed us that the rvr to 4R was still at 12oo and asked if we could accept that. We quickly agreed that we could and would like vectors for that approach. Again its all asses and elbows in the cockpit because we just got done performing a missed approach and now we have to set up the plane for an approach to a different runway. While getting vectors for the new runway, we re-loaded the FMS, tuned in the ILS, briefed the approach, re-checked our fuel situation and sent for new landing numbers for the new runway. We accomplished all of the required tasks and started making our way down an ILS for the second time. Approach handed us off to tower and shortly thereafter we were again cleared to land, the current rvr was 1200ft. We had just cleared the final approach fix when we heard tower clear an aircraft for takeoff. Tower then stated the rvr on 4R was 800ft. The Captain and I exchanged looks and both agreed to continue the approach to the decision height. Once you are inside the final approach fix, you are still legal to continue the approach even if the visibility gets reported less than the minimums for the approach. The autopilot was doing a good job of tracking the localizer and glideslope and I was keeping the speed pegged right at our ref speed. At 200 feet to minimums the Captain announced he was going heads up. I slid my thumb over the autopilot disconnect button and started to prepare for go around number 2. We were about 40ft from DH and I was just getting ready to go around when the Captain announced "Runway in sight, my controls" I quickly glanced out and could see the approach lights whizzing by in the fog below. A split second later the runway appeared and just as "Chuck Roberts" called "50" the Captain retarded the thrust levers and started to flare for landing. I could see a few stripes of the runway centerline in front of us, but that was about it. We were cleared to taxi off the runway at taxiway V and contact ground. We crawled down the runway and finally saw the taxiway. We made the turn and told tower we were clear of the runway. We flipped over to ground and told them where we were and what gate we were going to. He cleared us to taxi to the gate. I left the landing lights and strobes on because it was like soup ou there. We couldnt really see a whole lot in front of us. We slowly made our way to the gate, pulled in and shut down. I think both of us were a wee bit sweaty because that was one eventful flight.
posted by Windsor at 2:14 PM
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