Our Tattered Infrastructure, Updated and Corrected

I mentioned yesterday a friend's sighting of a mismatched American Airlines airplane at the Miami airport. Most of plane painted one way; nosecone painted another way.

Read John Shepley writes to say, au contraire! That "nosecone" is actually a radome (for radar dome), and there's even more to know about it, as follows:

The appropriate term is 'Radome' rather than nosecone. The difference is important. A nosecone would imply a physical, structural part of the airplane and might be made of metal - or some material with the preference to structural integrity above all other characteristics.

A radome is constructed to allow the passage of both outbound and inbound radar (radio) waves with a minimum of signal loss and distortion. Usually they are constructed of a fiberglass-reinforced plastic or Kevlar material. And they must be tested to ensure they are specifically compatible with the weather radar in the aircraft. And , of course, they must be strong enough to withstand the forces of normal operations, rain, hail, lightning strikes, etc., and maintain flightworthiness. As such they are enormously expensive and also must be painted with radar compatible paints. And they are quite bulky. Radomes are more susceptible to damage from a lighting strike than the rest of the airframe. Often, lighting will pass into and right back out of the conductive skin of an aircraft with little or no damage. The radome is a non-conductive dielectric, and the lighting will 'blast' it's way through on its way towards an offsetting charge. Most radomes include lighting arrestors of some kind, and they help, but do not provide immunity to lighting damage. The ridges on the P-3 radome shown below are the lightning protection. Note that they served to channel the lightning back to the A/C skin, but did not completely protect the radome from damage. Of course other kinds of physical damage may impact a radome more than other areas of the aircraft because of its location and construction. [Picture of Navy P3-Orion with lightning damage to radome, below.]

It's not surprising, nor is it much of an indictment on our airline industry that a new or limited edition paint scheme might not have properly painted spares at all parts depots. If a radome needs to be replaced, they'd have to use what they have on hand to maintain flight operations.

Another damaged-radome picture after the jump.


Also from John Shepley, what the front of an MD-82 airliner can look like after a lightning strike:

Now we know.