Captain Mike Bowers is chief pilot at our Newark Liberty International Airport (EWR) hub. This United Hub series is based on our column in Hemispheres magazine, in which Mike answers questions from our customers. Every month, we feature a few new questions and answers. This month’s Q&A is all about aircraft.
Q. Do you know how Boeing is able to fly a new narrowbody 737 to carriers located in foreign markets? How do they overcome range limitations in order to deliver the new plane from Seattle to Tokyo, for example?
A. The repositioning flights are planned with stops at airports along the way. The new generation B-737’s have a good range and they are flown with no passengers and cargo which extend the range even further because the reduced weight requires less fuel burn. I remember back in 1984 when I flew an empty B-727 from San Francisco to Newark non-stop. That aircraft would never be able to fly a trans-con flight with a load of passengers and cargo.
Q. Typical wind patterns flow from west to east, or vice versa at different altitudes. How does the airplane react while flying a north-south route or south-north route? Do you have to compensate for the wind coming from one side of the plane only? For example, say you're flying from LAX to SEA. Do you constantly have to "steer" the plane to the left in order to fly straight?
A. The typical flow of wind in the USA is from west to east, but the Jet Stream, which is a major wind pattern, tends to dip south around the middle of the USA and then head northeasterly as it reaches the east coast. It is not uncommon to have strong wins out of the southwest along the east coast. So we have to deal with winds from all directions. The way we do that is exactly as you suggested. If the wind is coming from the side of our intended route, we have to point slightly into the wind in order to stay on course. This is called “crabbing into the wind”. So if we wanted to fly directly north (360 degree track) and the wind is coming from the west, we may have to steer a heading of 340 degrees to obtain a track of 360 degrees. The 20 degree difference between our “heading” and “track” is called our “crab angle”.
Q. How close can two planes come face to face during a flight, like two cars in a highway going in opposite directions?
A. Aircraft are separated both vertically and horizontally. For flights conducted under Instrument Flight Rules (which all airline flights are), the minimum separation is 1,000 feet vertically. In most cases the traffic directly above and below you are traveling the opposite direction, odd altitudes heading east and even altitudes heading westerly. All of our aircraft are equipped with a system that shows the pilots where other traffic is located and alerts both aircraft if the required minimum separation is not achieved.