ASOS Machines and their role in Flight Planning

Automated Surface Observing Systems program is a joint venture between the National Weather Service, the FAA and the Department of Defense. As the nation’s primary surface weather system ASOS largely replaced the trained weather observers who used to reside in the control towers at our nation’s airports.

The ASOS machines give the NWS a better, more reliable means of weather reporting and forecasting by simply providing them with a plethora of data, collected hourly,  or as necessary, at over 1700 different locations in the United States.

But the reality is weather data is collected at airports because it is such an critical  element in aviation.  And while the automation of weather collection and reporting can help the NWS in providing more accurate forecasting, the limitations of the technology sometimes can impact us as pilots

George Carlin's "Hippy Dippy Weatherman" Al Sleet used to say ” The temperature at the airport is 88 degrees which is stupid because I dont know anybody who lives at the airport”.

The primary limitation with ASOS in my mind is the lack of peripheral vision at the receiving station. When the devices look skyward their sensors only see what is directly above them. If there is a hole in the clouds directly above the machine it will report sky clear. If the visibility is reduced this can be a problem. Everyone has had an experience where one end of the runway is clouded over or fogged in and the other is clear and sunny.  I remember numerous trips I have made where we were IMC and the ATIS at many of the airports along our route were reporting sky clear below twelve thousand feet.

Looking at METARS which are solely derived from ASOS we can see where along our route of flight the weather is folding helping us determine where the frontal activity is at a given point in time and geography. 

A holistic approach to weather evaluation should be made prior to embarking on a trip of any length. In fact it is a required preflight obligation of anyone desiring to operate an aircraft as Pilot in command.

Sec. 91.103 — Preflight action.

Each pilot in command shall, before beginning a flight, become familiar with all available information concerning that flight. This information must include—

(a)  For a flight under IFR or a flight not in the vicinity of an airport, weather reports and forecasts, fuel requirements, alternatives available if the planned flight cannot be completed, and any known traffic delays of which the pilot in command has been advised by ATC;

Starting with the commercial forecasts at cities along your proposed routing will present a picture of the prognostications of the forecasters. I’m fond of www.weather.com’s 10 day forecast.  I compile a list of cities across where I am heading and bookmark them in my browser.  I also use a NOAA site called HPC Sea Level Pressures and Fronts through Day 7  (http://www.hpc.ncep.noaa.gov/basicwx/day0-7loop.html) to determine why the weather channel guys are saying what they are. Essentially this site gives you a picture of where the forecasters are saying the pressure systems and fronts will be positioned across the contiguous United States from now through for the next seven days. The first four panes will look familiar to most of us as it is essentially the surface prog charts from the ADDS site. 

Seeing the pressure and fronts and their forecasted movements and comparing this to the commercial forecasts across the routing gives you an overview  picture of their best guess of what will be happening weather wise in these locations. Checking in with these regularly in advance of your departure will allow you to formulate alternate routings based on where the foul weather will not be on the given day you decide to launch.   Be mindful that forecasts are considered so unreliable, by the folks that create them, that they are updated every six hours. By examining them in advance you can gain some insight as to whether the weather is moving along as expected, in advance of the expectation or behind it.

Once our preflight weather planning is complete and we make the decision to fly we pick our route, check the most current weather across that route and launch.    

Light piston aircraft make best power at around seven thousand feet. Not to say that you can’t climb higher than that but you lose power in a naturally aspirated airplane.  So climbing above the weather isn’t an option as it would be for a pilot flying a transport aircraft, turboprop or light jet. Rather those of us in the piston single/multi class have to fly through the weather or under it.

Using the WXWorx /XM weather most of us have in our airplanes these you can see in near real time what the weather is doing along your route of flight allowing you to alter your plan well in advance of encountering conditions you might not want to fly in. If you don’t have weather in the airplane you fly in I would suggest getting it. A new Garmin Aera 510 with XM is about $1200 and the middle of the road XM subscription is about $60 per month. In mind this is as essential to instrument flying as a good pair of active noise cancelling headsets. Since I’ve been flying with it (2006) I have become so accustomed to having  this information at hand that I am uncomfortable flying in clouds without it.

Seeing the METAR icons change from Cyan to Green then Yellow and Red in a broad swath along your route of flight or at your destination prior to arriving there will help you make informed inflight decisions long in advance of encountering adverse conditions. Gone are the days of leaving the frequency to speak with a flight watch briefer as you barrel along towards your destination which unbeknownst to you went low IFR an hour ago. You can see where the weather is and plan to stop short add fuel and continue or change your destination before you actually needing to.

The New Normal

My favorite expression about the weather here in southwestern Connecticut is  “ we have nine months of ice and three months of thunderstorms”. If you were in the area last Thursday around 4pm you would have seen a spectacular example of a squall line preceding the cold front that descended through the state. The temperature at 6am was 74 degrees. It reached 89 degrees by 2pm and stayed warm and humid with reduced visibility in mist until the storms hit. The temperature at 7pm had fallen to 65 after the frontal passage.  I was over at Reliant Air covering the Mooney around 3pm when I snapped the shot attached to this email. The sky looked sick with a grey/green hue the heat and humidity were oppressive. When the winds started picking up a look at the nexrad showed what was beyond the low visibility, a massive line of storms. I was done for the day and started heading home. It took me close to an hour to complete a twelve mile drive.  When I turned onto my street which was littered with downed tree limbs and power lines it was the hail that surprised me.

Hail is in uncommon event here in the northeast. And to hear it smashing against the windows of my car as it mixed with the heavy rain it reduced the visibility to near zero. Following a neighbor’s taillights up the street and weaving to avoid the downed tree limbs and debris I started wondering if I was going to make it home or have to walk. That was an odd feeling, one I usually get when the snow is heavy on Pine Hill during the winter. Like this past winter, where we had record snowfalls and snow cover from early December on till the beginning of April

Anyway we’re living in our three months of thunderstorm season and looking at this past one plus the storm that spawned the tornados in Springfield a week or so ago it looks like this one may be a doozy. As a pilot and a flight instructor, who depends on flyable weather to make a living, I’ve been wondering what is going on with our weather.  I saw the following in a Reuter’s feed in May

"It's a new normal and I really do think that global weirding is the best way to describe what we're seeing," climate scientist Katharine Hayhoe of Texas Tech University told reporters.

"We are used to certain conditions and there's a lot going on these days that is not what we're used to, that is outside our current frame of reference," Hayhoe said on a conference call with other experts, organized by the non-profit Union of Concerned Scientists.

Hayhoe, other scientists, civic planners and a manager at the giant Swiss Re reinsurance firm all cited human-caused climate change as a factor pushing this shift toward more extreme weather.

While none would blame climate change for any specific weather event, Hayhoe said a background of climate change had an impact on every rainstorm, heat wave or cold snap.

"What we're seeing is the new normal is constantly evolving," said Nikhil da Victoria Lobo of Swiss Re's Global Partnerships team. "Globally what we're seeing is more volatility ... there's certainly a lot more integrated risk exposure."

The involvement of a reinsurance executive in a climatology conference adds extra credibility to a subject that a lot of us don’t want to admit is happening.  Bottom line our weather is changing and as pilots we have to deal with that.

Encounter with a Thunderstorm

“Cleveland Center Mooney 58Victor is requesting one zero thousand”. “Mooney 58Victor Cleveland unable ten thousand the military has it reserved for refueling operations”.   

Westbound at eight thousand the saddles between the buildups we had been weaving through started to exceed our altitude. By climbing to ten thousand we could likely still circumnavigate them.  Directly in front of us were three sizeable towers, one to the left, center and right. All looked to be about the same height- yet the one in center was closest on course. Glancing down at my brand new Garmin 396 that had been hastily attached to the yoke, minutes prior to departure, the XM display showed no cells or precipitation ahead. So I turned and said to Judy ‘tighten your seatbelt honey we’re going in”

We had left an hour and a half ago, well past our expected departure time. The trip was from Danbury Connecticut to Cleveland’s Burke Lakefront and was the first of a multi leg journey to Airventure Oshkosh in our 1975 Mooney M20F Executive.  We had made this journey in the Mooney six  times before. Our plan was depart at 9 am for the two and a half hour leg across Pennsylvania arriving into BKL just before lunch time. The weather forecast was typical for late July in the northeast. Visibilities were reduced in the morning by fog and mist burning off to a broken layer of clouds, with the potential for thunderstorms to develop as the heat of the day progressed. The plane had already been packed, all that was needed were the pilot and passenger to get in and go. 

Waking at 6AM the weather was checked and a briefing obtained. Our plan was to have lunch at Hornblower’s on the lake, spend the afternoon at the Rock and Roll Hall of Fame, an early dinner at the Chophouse and then catch an Indians game. We’d spend the night in Cleveland prior to continuing on to Oshkosh the next morning.  We planned to meet a friend in Cleveland who had complimentary tickets to both the museum and the ball game and for that we were to supply the dinner.

Checking in with the office both my wife and I had a series of small fires that needed to be fought prior to us being able to go so-we tended to these as quickly as possible while the hands of the clock moved around the dial. Finally at 11am the battles were won and the ride to the airport was made while finishing calls.

Flight Service provided an update briefing and the METARS across the route were all reporting sky clear below 12000 feet visibility 5 in mist. Departing VFR off of runway 8 at DXR and turning down wind the plane was barely out of the traffic pattern when we started encountering rain and lower clouds produced by the falling precipitation cooling the air to the dew point. My wife asked if we were going to be able to fly the trip visually and frankly I didn’t think so.

Picking our way along VFR until west of the Hudson River, a call to New York departure and a request was made for an IFR clearance from present position to Cleveland. The controller provided a squawk code and once in radar contact cleared us direct to Allentown direct Burke Lakefront at four thousand. We felt better on an IFR plan not being big fans of flying along low in low visibility. On top at four for about 50 miles the tops started encroaching our level, so subsequent requests for six and ultimately eight thousand were made.

With the clouds growing faster, I kept looking for information on my new XM weather device. It showed no precipitation, lightning or cells ahead.  When Cleveland Center announced that a center weather advisory and convective sigmet had been issued for the area we were in, rather than altering the plan by setting down and rechecking the weather in the local FBO  like we would “pre- XM”, the decision was made to press forward based on the semi real time information that was being beamed to the airplane via satellite.

We entered the center buildup and for a few minutes everything was normal. Suddenly  the vertical speed indicator started presenting a 2000 foot per minute climb that the altimeter agreed with. I had reduced power to maneuvering speed a prior to penetration and had it nearly pulled back to idle, yet we were still ascending at an astonishing rate. I applied most of what I had been taught about keeping the wings level -maintaining attitude not altitude and tried to keep the heading somewhat constant. I remember thinking if it didn’t get any worse than this, we might be all right.  When the rain and turbulence kicked in along with the updraft it became a handful. The rain sounded like a wood stove burning with the flue wide open but twenty times louder. With the turbulence throwing us into alternating 30 to 45 degree banks the sound would change dramatically when the rain would strike  either mostly aluminum or Plexiglas.   

Regardless of what was going on outside I was singularly focused on keeping the plane upright and the reality of a loss of control situation started creeping into my mind. For a moment I felt like just giving up and letting go of the airplane as it was getting increasingly difficult to keep it upright and heading west. As that thought crossed my mind I remembered Judy- sitting calmly next to me, confident that her husband, friend and pilot would take her on another great vacation in our little airplane. Picturing her lifeless body, dead in the wreckage, surrounded by our camping gear in the smoldering hulk of aluminum and steel was the motivation that snapped me back into reality. 

“Cleveland Mooney 58victor is climbing” I transmitted, to which the controller replied “58Victor VFR?” “Negative sir IFR” and he asked if we thought we could make twelve thousand. Still in the updraft I brought the throttle in and passing through eleven eight suddenly we popped out of the west side of the buildup.

What we came out into was brilliantly clear blue skies with the sunlight brightly illuminating everything including the canyons of towering cumulus we were ensconced within.  I went to set the prop to cruise and Judy said “Oh my God Sean your hands are shaking”.  On looking at the Garmin 396 it was now displaying bright red, orange and yellow blobs surrounding our position, emblazoned with little yellow lightning bolts. This completely blocked our way into Cleveland. I queried the controller when I reported level at 12000 and he replied that he could likely vector me around most of it.

Judy then shared her opinion,  “I think we should land,-closest place”. I hit the nearest button on the KLN89B and it came up with Port Meadville Pennsylvania six miles off our right wing. I told center that we wanted to divert to Port Meadville and he hastily replied “contact Youngstown approach now on 133.95”. I called Youngstown and they cleared us “direct Port Meadville descend four thousand”. We were briefly relieved until realizing that this required descending eight thousand feet in six miles, through the very same clouds we had just flown through. As I started steeling myself for the ride back through the clag Judy shouted “look a hole”. Banking right I spotted a two mile wide hole in the clouds, through which we could see the surface.  Pulling the power back to enter a right steep spiral the Mooney corkscrewed down from twelve thousand. On reaching four thousand we headed direct to Port Meadville  scraping the bottoms of the broken to overcast deck. We called Youngstown when we saw the field and he cleared us for the visual, stating he had 5 other planes that were diverting there- we cancelled IFR so he could start working the rest of them into the field. We executed another steep spiral from key position on downwind.  Rolling off that at 1000 AGL we flew a normal pattern and landed. Safe on the ground we shut down and were amazed at the cloud of airplanes appearing out of nowhere and landing, all taking refuge from the impending storms. We spent the night in Port Meadville and continued on the next morning. I received a text from my friend we were supposed to meet. His flight had arrived into Hopkins eight hours late and he was apologizing for not meeting us.  I told him not to worry about it as we never made it into town.

When Cleveland center wouldn’t let us climb any higher the inevitability of flying in bad weather manifested itself. We had been in and out of IMC since departure and being “instrument equipped and capable” this was no big deal. Rather, our inability to determine which of the clouds we were traversing contained convective activity was impossible due to the reduced visibility of flying down low.

Our plan to depart early in the day before the moisture, heat and instability had a chance to create the cauliflower shaped towers we were looking up at was valid and prudent. However life’s demands put off our leaving till late morning. By not fully taking into account how much time had elapsed while we were taking care of business, I chose to depart anyway, after all “it was still morning” and “only a two hour leg”. That was all the justification I needed to make a bad decision.  Having onboard weather was another distraction thinking we had a magic crystal ball visibility towards the weather.

The incentive of free tickets and hooking up with a friend, far from home, also clouded my decision making process as was proving to our friend that this little airplane hobby we had-didn’t make us crazy. By meeting him somewhere that he needed the airlines to get to was another misplaced incentive to continue on in weather that was beyond the capability of the pilot and possibly the airplane. You’ll never know you’re in over your head until you’re over your head. How you react to the knowledge once you’re committed determines whether you end up trying again or become an entry in a NTSB report.

We departed Port Meadville at 730 am the next morning and flew through some benign weather. At six thousand feet we were in and out of the clouds, stopping in Rockford Illinois and then into Oshkosh where we flew the VOR 27 approach. It was a complete IFR journey but we briefed and planned it as such so there were few surprises. We set up our camping gear and had a wonderful week with friends old and new at Oshkosh.