Accident Case Study: Trapped in Ice
It's the morning of April 16th, 2018, and a Beechcraft Bonanza, November 9345-Quebec, is flying IFR over central Ohio. The pilot and his passenger are en route to Deland Municipal Airport in Florida. Instrument conditions prevail in the airplane's current location, and the Bonanza is accumulating light rime icing at four thousand feet. The pilot descends to three thousand feet to clear the clouds and hopefully eliminate the ice. Okay we're underneath the clouds right now looks like it's clearing up. We're about one degree
over Celsius. November 4-5-Quebec roger thank you. About one minute later, the controller notices that the Bonanza has further descended to two thousand seven hundred feet. November Four-Five-Quebec, low altitude alert check your altitude immediately. The MVA in your area is two
thousand nine hundred. Okay right now we've been getting some buffeting. We've got some rime ice but we're losing. November Four-Five-Quebec roger do you need to land? Uh negative right now we're - we're clearing up. Roger. We're about four degrees over Celcius zero now. Roger. November Four-Five-Quebec uh use caution the MVA in that area is two thousand nine hundred. Yeah i understand two thousand nine hundred Four-Five-Quebec thanks.
Despite the pilot's assurances, the Bonanza's descent continues. It's now at 2,200 feet MSL, only 1,000 feet AGL. November Four-Five-Quebec how you doing sir? Uh we're doing okay right now. Waiting for this ice to dissipate. It's the last transmission the pilot will make to the controller. A minute later, the airplane's altitude shows 1,500 feet before it suddenly disappears from radar. The Bonanza impacts terrain near the town of Warsaw, Ohio, killing both the
pilot and his passenger. Sadly, these aren't the only lives that will be claimed by icing in the days ahead. A mere 200 miles to the east, another fatal aviation accident will soon unfold. It's now April 19th, three days later. At Lancaster Airport in Pennsylvania, a Cirrus SR22, November 451 Tango Delta, is preparing to depart on an early morning cross-country flight to South Bend International Airport in Indiana. The private pilot and his passenger are traveling to attend a conference being held at an Indiana University.
The pilot obtained a weather briefing using ForeFlight at 9:27pm the night before, with a planned departure time of 6:45am this morning. The graphical forecast products from his briefing predicted cloud cover as low as 2,000 feet MSL (around 800 – 1000 feet AGL) along the route of flight, and the surface forecast predicted marginal VFR conditions with likely snow shower activity. Meanwhile, terminal forecasts for several airports along the route of flight called for IFR and low IFR conditions during the airplane’s passing time. The ForeFlight briefing also included AIRMETs for IFR conditions, mountain obscuration, and moderate icing at various levels. However, these AIRMETs were only valid until 5:00am on April 19, which was before the intended departure time. After receiving the weather briefing,
the pilot filed an IFR flight plan with a planned cruising altitude of 6,000 feet MSL. Now, at 7:34am, the Cirrus begins its departure. The 500 hour pilot is instrument-rated and current, with 28 hours of actual IMC logged. In the last six months, he's flown four flights with his instructor for the purpose of maintaining instrument currency and proficiency.
Although last night's weather briefing warned of unfavorable conditions along his route, the pilot has decided to proceed with the trip. However, there's a troubling omission in his flight planning. An updated AIRMET advisory was recorded via the flight plan identification number at 4:52am, but there is no record that the pilot retrieved this new information. If he had obtained an updated briefing, he would see that hazardous conditions are now active during the time he'll be passing through. The new AIRMETs warn of moderate icing between the freezing level and 16,000 feet, IFR and mountain obscuration, and low-level turbulence, valid until 11:00am. Unfortunately, this Cirrus is not equipped with an anti-icing or de-icing system.
The pilot and his passenger, unaware of the new weather information, set off for Indiana. It's now an hour later. Cirrus 451 Tango Delta is about 10 miles past the city of Altoona, Pennsylvania, cruising at 5,500 feet, when the pilot makes a call to ATC.
Johnstown, this is Cirrus 4-5-1-Tango-Delta with a request. Cirrus 1-Tango-Delta, say request. Ah, just curious you know - if you know what the tops are of, of the clouds? I do not have any tops reports. Stand by. Let me call Center and see if they have any of that area. Okay, 1-Tango-Delta, Center has a tops report about 25 northwest of your position, around 17,000. 17,000 is the tops of the ceiling? Clouds? Ah, yeah. They said that that was, that
was the tops in that area. All right. We were just in a lot of IMC. What's the bottom? Is it 4,000? It could be lower than that. I'm showing, here at Johnstown, which is 18 miles southwest of you, we have - our, our cloud deck starts at 200 feet. All right. That doesn't help me. A minute later,
the reason for the pilot’s request to ATC becomes more clear. Johnstown, this is 4-5-1-Tango-Delta. Say again? This is Cirrus 4-5-1-Tango-Delta. We're getting a little ice up here. I think I should probably get down to Johnstown. Okay. So you want to divert to Johnstown, is that correct? Yes, sir. Can you vector me? 1-Tango-Delta, affirmative, sir. You're clear to Johnstown via radar vectors. It'll be an ILS runway 3-3 approach. Turn left, heading of 1-6-0. Actually, correction, make it 1-7-0 heading vector to the ILS. 1-7-0. And if you get the chance,
the type of icing you're getting, the intensity, and the outside air temperature, please? It's a little, it's a little - not bad, but it's enough to get me a little concerned. Copy that. Thank you. The pilot’s conversation with ATC indicates that he understands the severity of the situation, and he has decided his best course of action is to get on the ground. What runway am I expected to go into, Johnstown? 1-Tango-Delta, it's runway 3-3, the ILS, and we are, we are having traffic information Uniform. And we're showing a ceiling at 200 overcast, so that's right at the mins there for the ILS. If you still want to try it, that's fine. If not, I am showing Altoona's weather is a little bit better. They report -- or they're showing 500 overcast
right now. All right. Let's go to Altoona. With Altoona looking like the better option, the pilot alters his course. The airport is 25 miles to the southeast. 1-Tango-Delta, roger. Does ILS 2-1 work for you? That'd be good. What - can you vector me that? Yep. Absolutely. 1-Tango-Delta, continue left turn, heading 1-0-0 vector to ILS. 1-0-0. Think I could get down to 4,000? 1-Tango-Delta, descend and maintain 4,500. That'll be the lowest I can get you for a little bit.
4,500. Cirrus 1-Tango-Delta, advise when you do have the weather and NOTAMs at Altoona. And if you need me to, I can read the weather for you there. I can read the earliest observation for them. Yeah, if you could read the weather, that'd be great.1-Tango-Delta, not a problem, sir. The 1-2-2-6 Zulu observation: Winds 3-6-0 at 6; visibility 1 mile; light rain, mist; ceiling is 500 overcast; temperature 6; dew point 4; and the Altoona altimeter is 2-Niner-7-0. What
information is that? That's just off the ASOS there. It's an uncontrolled airport. Within the next minute, the controller notices the Cirrus changing its heading. 1-Tango-Delta, I show you turning about a 200 heading right now. Say intentions. I'm just going to try to get direct. What direction should I be? A heading of 0-Niner-0 when able. 0-Niner-0. Yep. I'll get it back on. Meanwhile, N451TD has been steadily descending past 4,500 feet. The Cirrus is at 3,900 feet when the pilot checks in. And you want me at 4,500? 1-Tango-Delta, affirm, sir.
Altitude 4,500 on heading of 0-Niner-0. A minute later, the controller notices that the Cirrus is still at 3,900 feet. Cirrus 1-Tango-Delta, the altimeter is 2-Niner-7-0. Just verify you're level at 4,500, please. All right. 4,500. I just dropped a little bit. I'll get it back up. Okay. Thank you, sir. It’s now 2 minutes later, and the pilot has only climbed to 4,100 feet. If his climbing difficulty is indicative of structural icing, the pilot hasn’t mentioned it to the controller. 1-Tango-Delta, turn 10 degrees to the left. 10 degrees left. 4-5-1-Tango-Delta.
Attention all aircraft, new Johnstown altimeter 2-Niner-7-1. Cirrus-1-Tango-Delta, turn right, heading of 1-2-0. 1-2-0. 4-5-1-Tango-Delta. The Cirrus continues to remain below its designated altitude, averaging 4,100 feet over the previous few minutes. Cirrus 1-Tango-Delta, 5 miles from (indiscernible). Turn right,
heading 1-8-0. Maintain at or above 4,300 till you're established. Clear to ILS 2-1 Altoona. All right. 4-5-1-Tango-Delta turn right to 1-8-0. We're clear for the intercept. Two minutes pass, and the controller sees that N451TD has crossed through the localizer course for runway 21 at Altoona. The pilot hasn’t realized the error.
4-5 - 4-5-1-Tango-Delta, you've already begun through the localizer, sir. Say intentions. Um, I still want to get there. Can you vector me one more - vector me one more time? 1-Tango-Delta, affirmative, sir. Maintain 4,500. Turn left heading 0-9-0. It'll be a box pattern back to final. 0-9-0, okay. I missed it. The pilot turns left, but continues his left turn beyond 0-9-0.
39 seconds into the turn, the Cirrus begins to descend and its airspeed increases. About 10 seconds later, the left turn tightens and the airplane begins to spiral. The Cirrus impacts the ground in a steep, nose-low attitude. Cirrus 4-5-1-Tango-Delta radar contact lost. Cirrus 4-5-1-Tango-Delta, Johnstown Approach. How do you hear me? A review of weather information current at the time of the flight revealed that the Cirrus most likely encountered IMC about 500 feet AGL on the initial climbout from Lancaster Airport, and remained in IMC and conditions favorable to icing for the rest of the flight. Before the flight, a forecast icing potential indicated that light-to-moderate intensity icing existed near the accident site, and a current icing potential product indicated that supercooled liquid droplets existed near the accident site. This weather
information was available in addition to the updated AIRMET advisory issued at 4:52am. The NTSB could not determine to what degree the Cirrus was affected by structural icing during the approach to Altoona. At minimum, it appeared to affect the airplane’s ability to maintain the altitude requested by ATC. In the end, however, icing was only one part of this fatal accident. While the pilot was
maneuvering in the last seconds before the crash, he was in IMC with restricted visibility. Combined with the spiraling radar track data and the high-velocity impact with terrain, the circumstances indicated the pilot was likely experiencing spatial disorientation. The airplane’s entry into a descending left turn while the pilot was being vectored back toward the localizer course, which subsequently tightened, became what’s known as a graveyard spiral.
The graveyard spiral can occur from a vestibular illusion associated with a return to level flight following a prolonged banked turn. There are a number of lessons that we can learn from this accident. The first and most obvious is that it’s imperative to check the most recent weather conditions before departing on any flight. A study of the forecast the night before a cross country is always a good idea, but it’s only one part of safe and thorough preflight planning. Weather is dynamic and ever-changing, and many aviation forecasts are updated every 6 hours, including AIRMETs and terminal forecasts. Flying with outdated information from a forecast 10 hours old is asking for trouble. Furthermore,
with the weather information he reviewed the night before, the pilot already knew about hazardous weather to come, and shouldn’t have proceeded with hope that conditions would get better. After all, hope is not a strategy for flying safely. A past-present-future approach can be helpful in identifying and predicting weather trends. For example, where was the weather yesterday or several hours ago? How long did it take to reach its current condition and location? And based on that, when can I expect it to improve (or worsen) along my route? Another critical lesson is the need to tell ATC what’s going on.
As the icing accumulated and the reality of the dangerous situation set in, small clues in the pilot’s language and actions were possible hints of his growing unease. It's a little, it's a little -- not bad, but it's enough to get me a little concerned. Think I can get down to 4,000? 1-Tango-Delta, I show you turning about a 200 heading right now. Say intentions. I'm just going to try to get direct. What direction should I be? It appears that the pilot desired a lower altitude with hope of finding higher temperatures.
It also seems that he knew he needed to expedite his approach to the airport, indicated by his intentional, albeit unapproved, change in heading. After the controller told him that 4,500 feet was the lowest altitude he could authorize, and questioned his heading change to 2-0-0, the pilot should have countered with more assertive language to make it clear what he needed. For example, “I need to get out of icing conditions, I need the lowest possible safe altitude, and I need the most direct course to Altoona.”
Going one step further and declaring an emergency would have been entirely appropriate. The high workload and stress the pilot was likely experiencing appears to have contributed to his failure to intercept the localizer course for Runway 2-1 at Altoona. It’s difficult to say whether the missed intercept had more to do with the icing conditions or the pilot’s instrument proficiency. Shortly following was the onset of spatial disorientation. The pilot’s spiraling turn and subsequent crash is a stark reminder of the insidious nature of spatial disorientation. It can affect any pilot, even one who is instrument-rated and current.
While some details of the pilot’s IFR refresher flights in the previous six months were published by the NTSB, we don’t know their true impact on the pilot’s proficiency. It’s important that instructors customize training to suit pilots’ individual needs and types of flying, especially during seasons of cold, snow, and icing. CFIs should conduct risk-management training using real-world scenarios to improve pilots’ decision making. This is an important component of the FAA’s Airman Certification Standards. We also don’t know how reliant the pilot was on using the autopilot in the Cirrus. The radar data showed that the airplane was flying a relatively smooth and consistent flightpath that was indicative of the pilot using the autopilot for the majority of the flight, until the final turn after flying through the localizer course. Another suggestion for instructors is to encourage the
practice of periodically hand-flying the airplane, to keep a pilot’s stick and rudder skills sharp. Finally, a small detail discovered during the post-crash investigation proved troubling. The NTSB found that the pilot had not removed the safety pin for the Cirrus Airframe Parachute System before flight. Removing this safety pin is critical to ensure proper operation of the parachute system. This is a standard Cirrus checklist item, and it appears three times – remove the pin during the preflight walk-around, verify it is removed before engine start, and verify once more before takeoff. We don’t know if the pilot attempted to pull the parachute before the crash, but if he had, it could have been a life-saving maneuver had the pin been properly removed.
The crash of November 4-5-1-Tango-Delta, as well as the loss of two lives in November 9-3-4-5-Quebec a few days earlier, is a sad and sobering look at the hazardous nature of icing, and the effects it has on both the aircraft and pilot. In the Bonanza accident, the pilot failed to obtain an official weather briefing. In the Cirrus accident, the pilot neglected to obtain an updated briefing. It’s a reminder to us that in general aviation, weather is one of the largest factors determining the safety of a flight. In today’s flying environment,
new technologies provide near real-time weather observations that can help us use the most complete information available to optimize our decisions. If we don’t use all of the tools at our disposal to make a full assessment of the weather, we put ourselves and our passengers at risk.
2021-01-17 00:05
