I know AEs use some kind of nonmetallic shank,
Actually, A/E uses a 360 degree welt eliminating the need for a shank. Shanks are used to anchor the breast area of the shoe (where the heel ends at the sole). Most shoes are welted 'breast to breast'; therefore the shank supports this area of the shoe. Contrary to popular shoe lingo, a shank does not directly support the foot, simply the construction of the shoe. The best shanks, I believe only now seen in bespoke footwear, are beechwood. Most now are some sort of acrylic, while others still use steel. However, even in shoes that use a steel shank, really it is mainly fiberboard with a heavy amount of mastic and a very thin (1/8") steel rod. I wear Gravati shoes mostly, and I have yet to set off a metal detector here or abroad - and they have this type of steel shank. I usually just shake my head no and walk thru - never have a problem at Dulles or JFK. Come to think of it, I really can't remember people being pulled aside to have shoes inspected in Europe (Gatwick, Malpensa, Linate, or Pisa anyway). Is it not as much a concern there, or have I just missed it?