Robert Swanson founded Airchime Ltd out of his British Columbia home making custom steam whistles.

There are a ton of horns that claim to be train horns out there, but there is no other horn out there that has the history, the size and the VOLUME of a Nathan Airchime Train Horn. The Train Horn of choice by railroad companies for decades, trusted to keep their conductors and their haul safe, is now available to install on your ride!

Nathan AirChime Train Horns have been ruling the rails for longer than most of us have been alive. In 1953, Canadian manufacturer Airchime Ltd refined its Nathan Truck Horn to be used on locomotives. The end result was the very first P-style Train Horns, also known as “The President’s Whistle”. The Nathan AirChime P-Horn took the rails by storm with its incredible volume, lower manufacturing cost, and little-to-no maintenance. The P-Horn has gone through many different changes over the years, with the three-chime P3 and the five-chime P5 being the most commonly seen today.

Shortly after the P-Horn’s introduction, the K- series horns made their debut in 1954. The K-Horn originally had a higher pitch than the P-horns and came in three chimes and five chime versions named the K3H and the K5H, respectively.

Back then, the “H” stood for “High Pitch”, though nowadays the “H” stands for “High Bracket” with the K5L having the ‘L” designator to indicate a “Low Bracket” style. Robert Swanson, who had designed both horns believed the K-Horn to be the superior horn, the P-Horn being the cheaper alternative.

In the 1970s, Amtrak wanted to bring the classic K-Horn to America's rails. While they loved the overall sound, they decided they wanted American train horns to be lower in pitch, altering the K5H from it’s original D# minor 6th chord to a much brighter and cheerier B Major 6th. Around the same time, AirChime had designed a new low profile bracket to mount the horns on. With the new tuning and lower bracket, the K5LA was born, the “L” standing for “Low Bracket” and the “A” to designate American tuning. By the 1980s, the K5LA was the most popular horn used around the world and remains so to this day.

P-series horns also include single tone (P1), three-chime (P3) and five-chime (P5) versions. The bells are sand-cast. Frequency ranges may be from 220 to 554 hertz. The P-series horns have longer bells and a heavier manifold than the M-series. The name of the horn is a P followed by the bells that face forward, followed by R if any are reversed, and then the numbers of the reversed bells; a P12345 is a true five-chime horn with all bells facing forward, while P135R24 has bells 2 and 4 reversed.

K series horns have many different eras and over time the notes were sharper or more flat.

In the beginning of The K series family in the 1950’s there was just the K3H and K5H which at the time had Adjustable backcaps with ”AIRCHIME“ on them. They were sandcast and sounded mellow, very close to a steam whistle which is what Robert Swanson originally intended.

When the introduction of the 3A and 4A bells in 1975 which would lead to the creation of the K5LA and K3LA they would be distinguished by their Big Tag which gave them the name of “Big Tag” Horns. Many of these horns played notes that were close to the intended and also not.

Wide Front Horns are from the 1980’s and are distinguished by the 3O1O9 on the back caps. Wide Front Horns usually play flat notes, but sound very sharp. For example the Wide Front K3LA/HA would play the E, G, C notes.

Narrow Front Horns started production in 1989 and were distinguished by the 30109 on the backcaps. A lot of the Narrow Front horns play chords similar to the Wide Front but as time went on they started to sound harsher. When the Raised Letter Horns started to pop up they still had the Narrow Front Backcaps until 2013 or 2014.

Raised Letter horns started production in 2005 or 2006 where Micro-Precision bought Nathan Airchime. Raised Letter Horns are distinguished by the “AIRCHIME” lettering on the side of the bells, and a lot of the early Raised Letters had Narrow Front 30109 backcaps until 2013 or 2014 as mentioned above. However newer Backcaps were made with a similar design to the older style Backcaps before the Wide Front design. Raised Letter Horns are also designed to play the intended notes of the horns they were meant to play originally. The Raised Letter K5LA/HA aka ”3rd Gen K5LA“ to railfans has a very high pitched sound to it because of the 5 bell, which has more prominence than that of K5LAs prior; this goes for the Raised Letter K5L/H as well. The KS-3A bells on Raised Letter K5LAs also tend to be sharp to some degree, playing closer to an A note instead of a G# note (forming a B7 chord instead of the intended major 6th), hence the name. The Raised Letter K3LA/HA and K3L/H sound Very close to their original intended chords. However both the Raised Letter K3LA/HA and K3L/H sound very similar to Leslie’s S-3K/RS-3K and the Prime-990 a copy of the Leslie S-3K with some notable design differences. This makes the sound of the Raised Letter K3LA/HA and K3L/H and other Raised Letter Horns very different from their predecessor K horns.

Raised Letter horns, especially Raised Letter K5LAs, are often derided by railfans for sounding very unpleasant when compared to the older horns. Some have said there is an FRA regulation mandating Raised Letter horns on the belief that unpleasant-sounding horns get more attention.