Removing an antenna from Sears Tower

[Al Skierkiewicz]

http://abclocal.go.com/wls/video?id=8729614
Last weekend, WLS removed the main Channel 7 analog antenna from the top of the East Pylon at Sears. This is a video of that event. The WLS traffic copter was used to shoot the removal. Of special note, one of the four men at the top was on the original installation crew for this antenna in 1985. As the camera zooms in and out, you will see significant parts of the north side of Chicago and occasionally, Navy Pier. As the antenna descends, you will see one of the glass blow outs on the observation deck and later you will see the major reconstruction of upper level Wacker Drive. For anyone who has been to downtown Chicago (or watched the Blues Brothers movie) knows there is an under ground street that runs near the Chicago River known as lower level Wacker Drive. It has been in existence for quite some time and was badly in need of repair.
All broadcast services on the roof had to be shutdown to prevent RF exposure to the workers. As you look at the video from the beginning, you will see each tower has three sections. Where the men exited the interior, is just above the Channel 11 (my station) old analog main antenna, now used by WBBM on digital Channel 12. The top of the antenna was removed earlier and it contained the tower aircraft strobe. The removal of the strobe was needed to connect the antenna to the helicopter. Note that the copter pilot must keep the aircraft centered over the antenna to prevent it from swinging and affecting flight.

[rsisk]

That just gives me the he be gee bees

[AlecMataloni]

Al, don't you mean the Willis Tower?

[cgmv123]

I saw the 3 minute news clip, but not the full video. Great work by the tower crew, the helicopter crew and the Chopper 7 crew that videotaped it all.

Did you all have to do a full shutdown or was it just a severe enough power reduction that to many it may have seemed like a shutdown? I wonder what the combined ERP of all the stations up on the Willis Tower is. I'm thinking around 4 megawatts. Far cry from analog, with what, 3 or 4 5 megawatt stations?

[FrankJ]

At last the real explanation of what really happened on Einstein!!!

[Barry Bonzack]

This is a video showing a helicopter pilot's Mad Skillz. Landing the tower into the back of an 18 wheeler, and placing it down gently can not be easy. Achievement unlocked.

[DonRotolo]

I guess a fear of heights is not in their vocabulary.

Clipped on or not, you need an awful lot of faith to do that.

Thanks for the clip Al, very cool.

[Al Skierkiewicz]

Yes, others will call it the Willis Tower, however, old habits die hard. I have been working in the Sear's Tower since 1975.
Everyone had to shutdown, radio stations included. ERP for single UHF digital stations is pretty high. We make about 15 kW to a 15dB gain antenna, so with losses in the feed line we are making nearly 150kW ERP. Most of the TV stations and FM stations are now on the Tower as the Hancock Center jacked rent a few years ago which got everyone to move. WLS as well as WBBM, maintain backup transmitters at Hancock so WLS broadcast the removal live. We had to shut down WFMT as well for the work. Leading up to the removal, many broadcasters also had to switch to standby antennas for several nights while other work was performed. The 4 MW ERP total number seems about right. In the analog world, UHF stations having ERP of a couple of MW was not unheard of. Of course, altitude of the antenna figures into the calculations.

[avanboekel]

Really cool video Al! I was downtown at the sox game earlier that day. Unfortunately they took it down well after the game ended. There was a perfect view of the tower from the top of the stadium.

[Dustin Shadbolt]

I've been up in the Sears tower a lot and still get a little freaked out from the view. I couldn't imagine going all the way up there and doing that. Great clip!

[Al Skierkiewicz]

I should have mentioned that the date had been pushed back several times due to winds aloft. The new antenna won't go up until after the Olympics as the local NBC station doesn't want to shut down during that period.

[Bob Bonczyk]

Watching this video really makes me like m
y job on the GROUND!

[Al Skierkiewicz]

Bob,
On a clear day I can see your house.

[Al Skierkiewicz]

Here is a link to the ABC website for the install of the new antenna. There are several short videos on the site showing various angles including one on the antenna and one helmet cam. The winds aloft picked up during the lift so it took a little longer than expected. It was going to be a two piece lift but since it took so long the helicopter had to go back to Midway Airport to refuel.
You will hear some of the reports talking about the "wedding cake". This was the first piece of the structure to secure the base to the top of the tower. That custom made piece was 4000 lbs. You can imagine an upside down cake when you look at it.
There are several videos on the page in this link. Kal Hassen is the Director of Engineering for WLS, a great guy and has been a standard in Chicago broadcasting for many years.

http://abclocal.go.com/wls/story?sec...ion&id=8837352

BTW, today was an interesting day for weather up high in Chicago. I will post some pictures when I get them transferred.

[NXTGeek]

Ha! What those guys did is nothing! I almost watched the WHOLE video...