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We were returning to Minneapolis–Saint Paul International Airport (MSP) in a Saab 340B from one of the outstations our airline served.
We had just been cleared for the ILS approach to runway 30R when a mayday was declared on frequency. My attention immediately tuned to the voice in my ear. A DC-9 ahead of us had just lost an engine having run into freezing rain. I felt my heart jump as I started to contemplate what we were about to run into. The first officer and I looked at each other in disbelief. Do we go around and divert to our alternate through now unpredictable conditions to an airport miles away? Or do we continue towards a runway only six miles ahead, hidden by water droplets that were now becoming quite hazardous. Just then the windshield wipers began to encrust rapidly in ice. Our decision had been made.
It has been said pilots may earn their full years pay in a matter of minutes, yet at that moment, they would trade that pay to be anywhere else. Today was that day.
We were returning to Minneapolis–Saint Paul International Airport (MSP) in a Saab 340B from one of the outstations our airline served. There had been a forecast for light freezing rain about an hour after our scheduled arrival. Our dispatcher had diligently filed Rochester (RST) as an alternate and even suggested we push early if able to get back before it arrived. The flight had been unremarkable for a wintery Midwest afternoon, typical with low ceilings and IFR conditions. Light icing in the descent, we had briefed the increased Vref speeds as we had many times before. It was the first officer’s (FO) leg to fly and I was the pilot monitoring. He was more experienced than the typical FO’s I had flown with. He had been at another regional airline for a few years prior flying a similar sized turboprop. The trip had been going well and I was confident in his ability. I was a new captain having upgraded about six months prior on the same plane that I had served my FO duties on. But that new 4th stripe was now pressing onto my shoulder.
Quickly we agreed our best option was to continue to land, prolonging our time in this icing seemed a losing bet. The Roselawn ATR icing incident in the back of our minds was weighing in now. We had already extended the gear and flaps to the approach setting. As the icing rapidly accumulated, we could tell the drag was multiplying at an alarming rate. It was taking almost 75% power now to continue on the glide path, typically it was in the 50% range.
Still four miles out, the windshield wiper arms were taking on the appearance of cauliflower, now encased in thick rime ice. Ice was creeping inward on the heated windshields of which we had never seen. The spinner was completely covered with ice, usually it covered about half of it. With the FO flying I was freed up to run the deice system. Normally the Saab had an auto timed cycling of the boots, about four minutes as I recall. Today, the ice was accumulating on the boots as soon as they deflated.
I decided I could use the manual function to blow the boots in an attempt to keep up with the rate of accumulation. The manual mode was activated by three little buttons on the overhead panel above me. I was just pushing them with three fingers each time the boots deflated and the ice would fly off and just and quickly start to build again on the leading edges. While the boots were doing their job marvelously, we could not see the danger lurking on the wings.
Ice being shed from the propeller sounded like rocks hitting the fuselage.
Wack! Wack! It was like the sound of rocks hitting the fuselage. My adrenaline hit a new high. The propeller deice was on high, and as it shed its accumulation of ice, it was impacting the fuselage about three feet behind us. Ironically three feet behind us is where the galley ice buckets held a more benign form of ice than was threatening us outside.
Now about four miles out, we are still in an opaque world, hearing the DC-9 had landed. Every flight behind us was now diverting and the controller was busy shipping them off frequency towards their diversions. The FO and I quickly agreed that we would leave the flaps as they were and fly it onto the runway as it was. While I can’t recall the speed, it was well over the normal range (160 kts perhaps). I asked the FO how it was flying, as he had turned off the autopilot shortly after entering the freezing rain. He responded that it was not being ill-behaved as we continued towards the runway. The encumbered Saab was trying its best to stay aloft.
We broke out around minimums, welcomed by the warm glow of the approach lights and drove the Saab right onto the pavement with no attempt to flare, not knowing if the wings had any margin of lift left before stall. After the abrupt shuddering, the FO brought the props into full reverse, with that low pitch whirling sound change from the blades now rejecting the oncoming air they were just previously clawing at to keep us moving. It was comforting to feel the forward strain against the shoulder straps as we slowed to taxi speed.
As we taxied off, we heard the airport was now closed to operations. At the gate, and after deplaning our unsuspecting passengers, we had time to inspect the aircraft. It was then that the true danger revealed itself.
While the boots worked as the designers intended, ice had accumulated well past the boots. Insidiously from the trailing edge of the boots to about 10 inches back on the wing underside, there was very course accumulation of rime ice. It was about the size of raisins, pressed onto the surface.
The unprotected leading-edge surfaces had over one inch of ice that had formed shallow concave to flat surfaces. The nose was covered from tip to windscreens in the same rough textured drag inducing accumulation. The top of the wing had smaller accumulations aft of the boots.
The unprotected leading-edge surfaces had over one inch of ice and the top of the wing had smaller accumulations aft of the boots.
A year later, with ice safely contained in my glass, I read a paper published by Saab Aircraft AB, “Summary of Saab 340 and 2000s Ability to Fly in Icing conditions.” It was an eight-page description of the Saabs flying characteristics while in icing and the testing performed on it. The last page had a statement confirming we had encountered severe icing from the freezing rain.
It states that icing on the spinner from the tip to more than half the distance to blades is the visual cue to the presence of freezing rain. Supercooled large droplet (SLD) is indicated by ice accretion on the whole spinner and aircraft nose. We had met SLD in person and looked it in the eye.
It also touts the Saabs resistance to accumulate ice aft of the boots and the excellent visibility for the pilot to monitor the wing if it did. However, our airline had white painted wings, and the bulk of the ice was on the lower side of the wing. As if hidden and lying in wait in the flat light of IMC conditions and lack of contrast. We will never know how close to an icing induced stall we were. If we had done one thing differently it could have changed the outcome.
Renowned aviation writer, Ernest Gann, recounts a story of a flight that he unwittingly escapes a fate that claimed others. An engineer expounds the details and calculations made on slide rules of how a similar situation resulted in fatal tragedy. In the end he asked the engineer if those slide rules could measure one man’s fate vs another.
Fate was hunting that day but somehow we remained elusive.
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SAAB 340 has been my favorite twin turbine aircraft since the eighties. Continental/Eastern were flying these out of Worcester Airport in MA to NYC on a regular schedule allowing me to leave home at 6:45 and be in my office downtown NYC at 9AM or earlier. Those flights were quick and easy and the 340 always flew like a giant sportscar in the sky. A conversation with a pilot at one point gave much credit to the handling of these fine machines. Retired now, I haven’t seen one in years but I know they are out there doing the work they were designed for. A truly great aircraft!!!
Well written account. Ernie would be proud.
Thank you, glad you enjoyed it.
Those who depend on luck to survive in aviation are destined to not survive! Freezing rain is one of the most insidious and treacherous killers regardless of the type of aircraft or whatever equipment may be installed. The simplest and also best response is to avoid it — go somewhere else to land and to live another day. Pilots who die in bad weather crashes are often buried three days later in sunshine!
Reminded me of my days in the Beech 1900. Still remember one particular approach into BOS picking up ice more than expected. Upon exiting the airplane was surprised to how much ice was still on the spinner, and looking down the engine inlet the amount of ice on the ice vane doors. First time I’d ever seen an accumulation there, and perhaps for the first time understood the significance of the ice vanes on the PT-6.
Those were great days of learning. 30 years on, I wonder if the current crop of airline new hires have lost something by missing those experiences or even appreciate the world before every regional operated jets
You are right Scott, there was a lot of learning from that type of flying and the curve was steep at times. I refer to it as my character building days.
Chris,
This is an excellent summary of not only the problem, but how to manage it. While the decision to continue or divert must always be situationally dependent, your description of maintaining configuration and flying onto the runway, without flare, is exactly what many, many pilots fail to do, leading to hard landings at a minimum. Your description of the limitations of wing color, and particularly ice aft of the boot on the underside, is spot on with many of the narratives I have studied. Take a look at NASA’s ASRS database, and look up ACN 934986. This describes a 757 which had pretty much the same experience you describe here.
Steve, thanks for your comments. I looked up that remarkable report from the 757 and it is eerily similar to my experience above. I commend that crew for their actions. These reports show how conditions can change rapidly and unpredictably at times and we have to take action with the information we have in a limited time. A well trained crew (or PIC in single pilot ops) working together is paramount to the success of a flight in challenging conditions.
Thank you, Chris. Who am I to say, but I’ll say it anyway: “excellent article.”
Greetings Chris — WOW! great job – you had me on the edge of my seat!
Unfortunately (or better yet fortunately)… been there done that – 1980 – Navajo Chieftain – delivery MEM to SEA – winter – Utah/Idaho skies……
Your are an extremely talented author — Keep it up!
Be safe,
Mario
Mario, Thank you for the kind remarks. I’m sure you story would be a good read as well. Single pilot in an icy Navaho must have been challenging.
That was the best “Saab” story I ever heard! The picture of the ice accumulation outboard of the engine in the boot gap is chilling. Let it be a lesson to those of us flying without boots or TKS systems!
Great article and flying. I also was with Mesaba but in the F27, Metro and Dash 8 days. Always loved the tough old F27. Not a sporty plane by any means but solid and dependable.
Good to hear from another Mesaba-ite Timothy. The F27 was gone by the time I got there but I heard stories about it from some of the Captains I flew with early on. The Dash and Metro were on their way out as I got hired into the Saab and the Avro was just showing up. We probably know some of the same people. Thanks for your comments.
I spent 15 years flying, teaching, and checking in the 340 for several carriers in the Northeast. For the most part it was a pretty good ice plane til… We were enroute to BOS and received holding instructions and told to expect about 30 minutes. As we descended in the holding pattern, I noticed it was it took more power to maintain altitude, not much but enough to be remarked upon. As we were released from the hold, it took almost 90% power to maintain 160kts. Way to much for the the clean wings (boots were working as advertised). As we continued inbound, the airspeed continued to decrease and the aircraft began to shake. It became painfully obvious, we would not be able to around the continue around the daisy chain to land using the ILS to 4R. About 10 miles NW of BOS, we declared an emergency and joined the ILS to 15R. It took almost full power to maintain 130kts on the glide slope.
We just made it. As we taxied off, we were met with the emergency vehicles and the local FAA Inspector. He walked up to the airplane as the props spun to a stop. He and I both saw all the ice that had built up behind the prop de-ice heating elements. The Saab has composite props and the heat from the prop de-ice do not transfer the heat to the prop as they do on a metal blade. Flying is about learning something new every flight. That day we learned about prop run back ice building up behind the prop de-icers.
Flew both MetroLiner and Dash 8 in more icing conditions than I can count. Your story brought back “chilling” memories of similar experiences. Godspeed!
GREAT ARTICLE! And most likely, many of us shared similar experiences to earn the year’s pay check on one approach. Well done!
I’ve had a few encounters with freezing rain but not at your level. I was either above the ice or had warm air below to melt it off.
Interesting, very interesting. About 24,000 hours DC3 to B767-300 and proud owner of a Piper ARROW III PA28R–201. It was the latter aircraft that had my eyes on storks after we landed. How come?
We had spent nearly an hour at 9,000 feet with an OAT of – 7-9ºC in lovely sunshine and it was soon time to commence our descent for the instrument approach. A step descent to the initial approach of 3,600 ft in cloud from at least 8,000ft wasn’t a problem we thought. Whew! what’s that? Now that is one way to get the Captain’s undivided attention. I’ve never seen that before. Upon entering IMC, just beyond my left shoulder, ice was forming at an alarming rate on the surface of the fuel tank. Our time at altitude had obviously cold-soaked our fuel which in turn encouraged us not to delay in any way our landing. Once on the ground, an inspection above and below the wing/fuel tank showed a great accumulation of ice. Our departure quite sometime later had the wing skin relatively cold to the touch but no ice. Fortunately, our departure was over the sea at Hokitika which made Plan “B” easy should we be delayed climbing back out to VMC on top. You never stop learning!