Captain Ken O’Donnell flies an Embraer 175 for Republic Airlines. Ken is also a former ATP Student, Instructor and Regional Jet Instructor and is currently a Career Coach with BeAnAirlinePilot.com. Ken shared an article that he wrote about professionally flying instrument approaches and I would like to share it with you.
“One of the most significant milestones during flight training is mastering the instrument approach procedure. That’s the process a pilot or crew uses to get the airplane safely on the ground when the weather is less than what you’d prefer for a day at the beach (clouds, low ceilings, fog, haze, etc). It’s also one of the most critical times in an aircraft – in a jet you could be traveling well over 200mph in the clouds, and fairly close to the ground. Thinking 3 steps ahead, following textbook procedures and maintaining good situational awareness are essential – terrain is always a concern, crosswinds or tailwinds have to be accounted for, and you may have to factor in nearby storms which could limit some options. In other words, the crew's workload is high, and room for error is low!
There are many types of approaches, which use ground instruments or satellite based guidance to provide a course to fly, and either an electronic vertical path (glideslope), or specific points to progressively descend lower. A google image search for “instrument approach plate” will show you many examples and I can explain some of their features if questions are posted in my forum. The “plate” is the graphical “map” of the procedure – on paper or even an iPad, showing the route, altitudes, locations, and limitations (speed, visibility, etc) relevant to the approach. An airport may have from one, to dozens of different published approach procedures, depending on number of runways, how advanced the facilities are, etc. There can sometimes be four or more different types of approaches for just one runway. Also, not all aircraft have matching capabilities to fly the provided approaches – this is sometimes why one aircraft can land in bad weather and another can’t.
Given all of that, instrument approaches are still broken down into two primary categories – precision and non-precision. Generally speaking, a precision approach gives you a steady and very accurate vertical and horizontal path to fly down to a point that’s often just 200’ above the runway (but can be lower in some specific cases... even down to touchdown with special crew procedures and equipment). Essentially, if you see the runway or approach lights at that moment (or prior) you can continue and land. If you don’t see what you need, you immediately execute a go-around and climb out, raise gear and flaps and fly the “missed approach” procedure on the instrument approach plate – these can be complex so you have to be well prepared.
With a non-precision approach, you don’t have precise vertical guidance and you normally cannot descend as low as a precision approach – heights from 400’ above the runway to occasionally over 1000’ in mountainous terrain can be typical. You’ll know when it’s time to stop looking for a runway and start climbing out by using anything from GPS info, to a calculated stopwatch time, to a quick math calculation of ground-based distance to the runway – all depending on the approach, aircraft, company procedures, etc. Proper procedure is essential here as it can sometimes be possible to see the runway when you’re directly over it at, say 500’ in the cloud bottoms, but trying to land a jet from that point will not work – ever! Either way, you have a few options when you don’t land that first time, and more than likely, you've been thinking about and planning for these options from prior to even attempting the approach.
Once in the airline world, planes rarely fly with full fuel loads. First, the more weight a plane carries (in extra fuel for example), the more fuel it burns (just like towing a trailer kills your car’s gas mileage). Second, large aircraft are seldom designed to carry both full cargo and full fuel at the same time... if you’re topped off with one; you have to limit the other. But, there are still specific FAA requirements for how much fuel must be onboard at a minimum. Very roughly speaking, on a perfect day you still at least need extra fuel for delays or issues you could encounter enroute. When the forecast is poor, you need that fuel plus additional fuel to be able to fly to a pre-planned alternate airport with an acceptable forecast, in case you’re not able to land at your original destination.
That all hardly scratches the surface regarding instrument approaches but hopefully begins to shed some light on them. It takes quite a few hours of study and even more practice in the aircraft and simulator to become proficient. I’ll post some interesting approach examples soon, including a recent 3-approach night that kept my First Officer and I pretty occupied.”