“Stack the odds in your favor by making sure your airplane is never pointed short of the runway after you leave the final approach fix.” – James Albright
Sounds simple right? No impact with anything other than a runway? Well, this post is about the surprising reality that until machines really do all the flying, we may have to do a little math, and avoid the temptation to dive and drive.
And just to emphasize how even a simpleton like me can learn this technique, we’ll conclude this post with the magic of the number “3” – the only number you’ll need to remember to keep it stable, safe and calm.
When I first read James Albright’s “Don’t Dive and Drive” I had the inspiration for a specific post: If I can do it – anyone can. Heck, I don’t even fly that much and I can do it. I just need to remember “3.”
The reality is that the way most of us were raised (I’m nearing the end of what I’ll term – “the last of the dinosaurs” that were raised on pencil, paper, E6B – the slide rule and yep, you guessed it the “dive and drive” non-precision approach.)
For the non-aviators out there let me lay out the story arc:
- It was once ok to fly an approach in step format, rather than a constant slope.
- We didn’t know any better since this was how we were taught.
- Airplanes, people and accident stats don’t like this and doing it makes no sense to do this at all.
Or think of it this way:
“When in a wheel chair – do you want to go down the stairs like a slinky? Or on a slide?
Big machines, flying through the air, should not, when close to the ground, engage in “dive and drive” methods of non-precision approaches. This means that rather than make a constant descent (like on a track that takes you to the runway) the dive and drive person flies an approach the way a slinky would go down the stairs.
Richard Laberge first taught me this at Missinippi Airways in northern Manitoba. The reality was that the very austere environment of being completely on your own in the Canadian north really forced you to examine your flying as you barreled into some remote dirt strip, at night, hopefully in good weather.
“It’s not safe man.” Richard started.
“Just do it like we do the Airbus at Transat, when we cross the fix, we have already calculated the rate of descent that we’ll maintain – all the way to the runway or missed approach point.” Richard was talking SLIDE….. Not stairs. And when you have a nurse, enough fuel for Winnipeg, two crew and your doing 130 knots in an old King Air – the slide is always preferable.
The instrument approach was a concept pioneered by the first souls brave enough to enter clouds without a plan other than they had a time and heading and rough idea of where they were and where they’d be when they started to “let down.” When they got to their destination, they formulated a “let down plate.”
I learned to fly from a 70+ year old in 1986 and he was old enough to use the word “well, when we got to Teterboro, I realized I didn’t have a let down plate.” His name was Beech Thurlow – yes, first name Beech, and he was not joking. A let down plate was a thing that originated with someone doing it by hand, on a good day. In other words “a home-brew approach.”
Those days evolved into something more official, and thanks to people like Jepp Jeppesen they became an actual publication. Ultimately the government got in on the act and they became a standard element of navigation. Let down plates, or “approach plates” today, are largely in digital format for an iPad, an FMS (Flight Management System) or paper you printed the night before in your planning for the next day’s trip. Until recently they were the giant books of approach plate binders you saw pilots hauling around the airport. You’ll note their carry on gear is getting lighter in the last 10 years.
We Evolved, Then We Stopped
So the evolution from just a hope and a prayer to formalized navigation was a big step. The evolution of AM radio signals as beacons to VHF omni directional signals allowed you to strap the airplane onto a virtual set of rails in the sky really changed things beginning in about 1946. In fact, approaches reached the point where the ILS (instrument landing system) was invented which afford a stabilized approach from a specific point 3, 5 or 10 miles back from the runway. The idea with the ILS was that you “rode the rails” in the sky of two VHF signals right to the runway.
But for the non-precision approach world (and this includes some GPS approaches today) the way to conduct the approach was to cross a certain fix (an imaginary but specific point in the sky) and then begin a descent to a lower altitude as you neared the runway.
The idea to avoid, as illustrated above here is to dive from FRALY at 2700 feet down to 2020 feet, and do that for 3.0 nautical miles before you dive again (from TIBIB) down to 1400 feet (a mere 500 feet above the ground!) for 2 nautical miles. Not a fun way to spend a whole minute, as the trees float below the passengers yet you see nothing out front, or maybe you do… but either way.. not safe to go down. See the problem here?
How It Can Hurt You
The key reasons why diving and driving is passé is quite simple: When you are on the approach to an airport, and for the business aviation people out there, this is important, MANY of your approaches to the far flung airports we go to don’t have precision approaches and sometimes they don’t have any instrument approaches. James’ article gives a quick summary of why diving and driving is really a subtle temptation into a CFIT (controlled flight into terrain) and ultimately a potential death sentence. Here’s a Reader’s Digest version of why always having a constant descent path is the new religion.
- Leaving a safe altitude with an aggressive descent requires you to be on top of your game – even the autopilot can get confused.
- We suck at judging distance, at night, in the rain / mist etc.
- Clouds and fog aren’t uniform – seeing the runway and starting down off the MDA early is a CFIT recipe.
- You don’t have to go back UP (fly the missed approach) until you are finished flying along the MDA (min. Descent alt.) this can lead to people diving at the runway at the last minute when you are too high.
- Pilots suffer from the “I must complete the mission-itis” …. So they wander BELOW the MDA on fishing expeditions… especially if they are comfortable on fuel and they are on their second pass (link to B1B accident).
The Take Away
Metaphorically, we live in an age where you can get your shoes tied by your iPad if you have the patience to download the app and buy all the gear.
Aircraft cockpit technology is no different. Situational awareness, automation and tools to make our job easier, safer where we are really good systems monitors is where things are headed. The stabilized approach is something that the FMS (flight management system) instrumentation can happily do if programmed and prepped in the right mode.
But, if you are flying old school and didn’t get around to learning how to make VNAV mode work in that device, that you just met for the first time yesterday, and the manual isn’t in the airplane (or on your tablet device shame on you) then you’ll need to resort to Adam’s caveman flying which Richard Laberge drummed into him in the primordial King Airs of northern Manitoba.
Thankfully for me, I only needed to remember one number: Three.
Using the rule of three I look at the picture below and say to myself: “I’d like to start down a 3 degree slope and that will mean losing 300 feet per nautical mile (at 120 knots). So… I’ll need to lose that over 5 nautical miles (the 3.0 between FRALY and TIBIB and another 2.0 between TIBIB and PEVGU.)”
So, the brain goes: 5 nm x 300 feet = 1500 feet to lose from the final approach fix (FRALY) to the missed approach point (PEVGU) which is at 1400 feet. So….cross FRALY at 1400 + 1500 = 2900 feet like our awesome sledding guy in red, and voila… a stabilized approach is born.
And why do jet owners, passengers and the flying public everywhere enjoy this smart approach to your non-precision approach management? Because at the end of it you’ll just keep the profile right to the runway, or if the weather is low you will go back up again.
Either way, you’re not bombing along in the weeds, looking, hoping and facing the temptation that happens when you’ve let yourself dive and drive.