A Wave Here?

I knew airspeed was everything and Id rather fly into a tree than fall into one.


I am an 1,100-hour instrument pilot flying an A-36 Bonanza. The other night, my friend Bill (a student pilot) and I were flying along in the Pittsfield, Mass., area and encountered a situation I had never seen before.

We were cruising along northbound VFR on top at 7500 ft. in smooth air and unrestricted visibility with autopilot engaged at 154 knots IAS. There was a broken layer below us with tops estimated at 6,000 feet. The winds at our altitude were from the northwest at approx 65 knots. Outside air temperature was right around 0 Celsius. The highest terrain in the area was about 4000 ft. The nearest weather front was a strong low hundreds of miles to our south.

In front of us we saw an area where a portion of the cloud layer was higher than the rest, but since we could see over it and around it we were debating whether wed need to climb or divert to stay away from it (and possible ice). I deferred the decision until we got closer. As a precaution I turned on prop and pitot heat.

A few moments later I noticed the airspeed declining and the engine began laboring as if in a climb. A scan of the instruments showed we were at level flight at a steady altitude. I verified prop amps on the slim chance that somehow the prop had iced up in clear air. I scanned the engine instruments and all of the readings were OK.

The airspeed continued to decline. I enriched the mixture a little, firewalled the power and tried the alternate static source. Airspeed was down to 100 knots IAS, still at level flight.

I disengaged the autopilot and started descending in order to maintain airspeed. I was now descending toward the cloud, which was now right in front of us, and I opted to turn right to avoid it.

All of a sudden, wham! We got sucked into this thing and lost 300 feet in a second. My head hit the side window and Bills hit the roof. We were now being tossed around in severe turbulence inside the cloud.

I did my best to level the wings and just fly airspeed and attitude. The airspeed was fluctuating +/-50 knots and the airplane being rolled and yawed from side to side.

All the while we were losing altitude despite full power and 100 knots indicated airspeed.

Since this had all the ingredients of a thunderstorm penetration except for precipitation, I was also very concerned about ice and hail, but there were absolutely no signs of precip whatsoever.

Bill pointed a flashlight at the wings and saw at most a trace of ice. Although we had hit numerous updrafts and downdrafts, the general trend was downward. At 6,000 feet I was getting very nervous about the terrain below us. Still, I knew airspeed was everything and Id rather fly into a tree than fall into one.

We were tossed around like we were in a washing machine. Some of our roll excursions exceeded 45 degrees of bank, and I attempted to work our way to the right without over-banking the airplane.

Then we popped out into beautiful smooth, clear air with lots of stars. I began the climb back to 7500 feet, apologized to ATC for the altitude deviation and reported the severe turbulence encounter.

Leveling off at 7,500 feet. I noticed my airspeed climbing well into the yellow arc. Once again I tried the alternate static source with no change. I verified pitot heat & retarded the throttle to get us out of the yellow. Gradually the airspeed came down and I was able to add back manifold pressure to normal levels. The rest of the flight was uneventful.

Thinking back, I have to conclude that the reason the motor sounded like it was straining and our loss of airspeed was due to a strong downdraft in clear air outside of the cloud, with the autopilot was fighting to maintain altitude. Upon exiting the cloud, we encountered a strong updraft in clear air, which would explain the increase in airspeed while in level flight.

Although Ive never heard of a true mountain wave in the Northeast, it seems that the symptoms meet the definition. Although the winds were strong, we were 3,500 feet above the highest terrain. Also, the updraft and downdraft were in clear air outside of the cloud and above the broken layer.

Other lessons to consider: A mountain wave is a possibility anywhere theres rising terrain, not just around 14,000-foot peaks. You dont say your relationship to the mountains, but if you were over them or downwind of them its a possibility.

As for the climb and descent, your attitude indicator should have given you hints. The autopilot trimming nose up to maintain altitude in a downdraft would have showed up as a nose-up indication on the gyro and the trim indicator. Ditto the descent.

One hint for avoiding such phenomena is to look at altimeter settings on both sides of the mountains. A big difference means big airflow.


Hard Lesson from Soft Field
I am very fortunate to be able to live, work and enjoy flying in the state of Florida. Along with tolerable temperatures, the fall and winter months bring with them exquisite blazing orange-and-red sunrises. I find myself most Saturday mornings on the field, conducting my pre-flight procedures in the dark, in order to witness yet another glorious sunrise.

On a recent Saturday, I took a friend on a mystery-trip breakfast flight to a well-known bed and breakfast property approximately 40 minutes away in central Florida. As a part of my safety routine with passengers, I advise them of any upcoming issues that might cause them undue concern during the flight. In this case, I knew that we would be landing on a grass strip so I told my guest that she could expect some minor bumps as we settled down after landing and slowed to a reasonable taxi speed.

The grade of the strip was somewhat unusual in that it was clearly uneven with dips at several sections. We landed without event and went in for breakfast. Little did I imagine that within a very short period of time, I would find myself struggling to leave this sleepy little strip.

With breakfast complete, I began our taxi for takeoff and positioned the airplane at the very end of the runway. I powered up with brakes applied and no flaps (as suggested by the strip owner), then let off the brakes and ever so slowly began to trudge like a turtle through high grass.

Within a few moments it dawned on me how the thick turf was trying to hold me to the ground like fly paper. As if that were not enough, there was a pond at the end of the runway, ready to baptize those poor souls that needed a good learning experience.

The aircraft rattled furiously as we forged our way through the turf. The airspeed indicator needle was slamming back and forth between 35 and 60 knots. Even the avionics toggle switch threw itself into the off position.

The pressure was on as we began to reach the go/no-go decision point. Believing wed made 55 knots I tried to rotate, but the airplane wasnt ready to fly. I relaxed the yoke to gain more speed on the ground and on the second rotation attempt we lifted off, with a slight dip over the pond. For three seconds after that lift-off, I truly believed that we were not going to make it out successfully.

Thinking back, I believe there were several factors that significantly affected the departure. We were in an underpowered two-seat aircraft. While we had no luggage, we were heavy with fuel and only slightly under our maximum weight. The thick turf caused enormous additional drag. The uneven ground also caused the instruments to become erratic to the point I was not able to accurately gauge the airspeed.

My ignorance of grass strips, having never landed on one, made me unprepared for what could occur upon departure. I should have asked if anyone had any advice. I quickly developed an enormous amount of respect for a runway that can be full of sneaky surprises.

The truth is, everything boils down to mathematics. And on this day, I was just numbers away from making a very, very serious error.

Other lessons to consider: An underpowered two-seater that needs 55 knots to fly without flaps … we suspect you were in a Cessna 152. If so, you might reconsider taking the advice of airstrip owners and consult your flight manual. You make no mention of using a soft-field departure technique, only a short-field technique. In either case, a notch of flaps is recommended for takeoff in a 152. Flaps wont hurt a high-wing airplane on a grass strip, although the wheels may kick up stones that ding a low-wing airplane some.

Just to refresh your memory, the soft-field technique gets you off the bumpy ground and lets you accelerate in ground effect before the airplane is ready for a conventional rotation. Learn it and use it before you go back to Chalet Suzanne.


CRM at Work – Sort of
While serving as a captain in the US Army in Ansbach, Germany, during the height of the military buildup in the mid 1980s, I learned a timeless lesson in what is now referred to as cockpit resource management.

In the military, the training pilots receive in emergency procedures, crew coordination and airspace management is certainly among the best in the world, if not the best. The training I received was tested on an early Wednesday morning when I was scheduled to command a UH-1 Bell helicopter for a routine flight from Ansbach to Wurzburg, about one hour flight time.

Dave (the co-pilot), Chris (the crew chief) and myself (the PIC) were scheduled to depart under VFR conditions as part of a four-ship mission transporting senior officers to a conference. The day prior, we received our briefing and planned for a 0900 VFR departure.

However, before going to bed I checked weather conditions and discovered the flight would have to be conducted in IMC. This would not be a problem as all the pilots were IFR qualified, current and competent. I called my co-pilot and we agreed to meet at the airfield at 0700, complete the preflight, file and launch precisely at 0900. Our aircraft would be the last of the four to depart.

At 0700 the morning of the flight, I arrived at our flight planning area to find Dave with a head cold and blocked sinuses. Local policy required two qualified and current pilots for IFR flight, this meant Id have to find someone – and in a hurry. Joe, another Captain, happened to be in early to catch up on some work. Although current and qualified, he was not comfortable with IFR flight and didnt have much experience. On the other hand, I was very confident in my abilities, flew often and felt assured I could make the flight single pilot if required.

We completed our preflight planning and went to the aircraft feeling good. The plan was for Joe to pilot the helicopter from the left seat and I would operate the radios and navigate from the right seat. Chris would sit in the jump seat directly behind Joe.

After the first three helicopters departed, we were cleared for departure. Joe and I conducted our final CRM checklist and briefing. The briefing consisted of required responsibilities, power settings, limitations and emergency procedures.

We took off and completed the after-takeoff checklist. I felt Joe was comfortable and in a stable 700 fpm climb, so I diverted my attention to changing frequencies, calling departure and cross tuning ADF frequencies. These actions required a heads down position in the Huey as all the knobs are on the floor-mounted pedestal. As I completed these actions I looked up to mass confusion.

The attitude indicator showed a 10 degree left turn, 20 degrees nose low attitude. The airspeed indicator showed 0 knots airspeed and the power setting was at idle. The VSI indicated a rate of decent of over 1,500 fpm going through 1,000 feet agl.

I attempted to take the controls and make corrective action but the controls would not move. Joe had frozen on the controls. We were headed for the ground and I couldnt overpower him.

After several unsuccessful attempts to communicate with Joe, Chris unbuckled, climbed over Joes seat and literally peeled his hands from the controls. This allowed me to manipulate the controls, leveling the aircraft and increasing power.

I moved the cyclic forward to regain airspeed but the only thing happening was severe vibrations bouncing around the helicopter. I pulled back on the cyclic and found my airspeed beginning to decrease. What had happened was that the airspeed indicator had gone full circle and was actually indicating 140+ knots of airspeed (well above Vne), not the 0 knots airspeed it was registering. We continued falling like that anvil we all learned about in flight school.

I continued to increase power, pull back on the cyclic and pray that we would make contact with the ground with the skids level. Throughout this 2- to 4-minute period, all of my communications were proudly broadcast over the Nuremberg Departure frequency. My finger was not sensitive about keeping the indent to the intercom notch. Several times throughout our decent, Nuremberg called to ask what assistance was needed and if we were having an emergency. I was oblivious to his calls and continued to transmit our internal communications to the world.

Good stories have good endings. We recovered at an altitude estimated by Nuremberg Approachs radar of less than 300 feet agl while still IMC and began a climb to safer skies. We climbed to 5,000 feet, broke out of the clouds and received direct vectors to Nuremburg International Airport some 30 miles away.

Once we were clear, Joe asked what happened. He did not have any recollection. We received an ASR into Nuremburg and Joe blacked out again as we descended through the clouds. I remained on the controls and Chris, well he sat on the pedestal between Joe and I until we had the airport in site.

We landed safely and lived another day to tell our story. The Huey, well because we exceeded just about every limitation of the POH, it was sent for a look over.

I initially wrote this over 15 years ago and filed it under my flying experiences. It wasnt until about three months ago Chris found me through an on-line search and we were able to meet and tell our kids the story. As we continue stressing the importance of CRM, we shouldnt forget about the inclusion of all crew members and, more importantly, the importance of detailed crew briefings prior, during and after the flight.

Other lessons to consider: We think the reluctance of your co-pilot to embark on instrument flight may have been his inexperience in part, but it should also have been a warning to you as PIC that all of your equipment may not be up to standard.

In retrospect, perhaps you should have been the pilot flying the departure and Joe should have worked the radios.


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