I never knew the answer to this: why were the 720's retired? Could they not be still in use like the few 707's? What was wrong with them?

You really don't know the answer? As far as I know, there are no 707 airliners flying either. The better question is why would they be flying.

OK, as seen as you asked, why would they be flying? And yes there are some 707's flying around, aren't there?

callumconroydub wrote:

I never knew the answer to this: why were the 720's retired? Could they not be still in use like the few 707's? What was wrong with them?

How many 707s do you know of that are in service? Airlines and routes?

The last Boeing 720 was retired in 2010. See: https://www.wingsmagazine.com/news/worl ... tires-4553

Only 154 Boeing 720s were ever built. Better and more economical aircraft came along (e.g. the Boeing 727), superseding the Boeing 720 and rendering it obsolete. That's just the way things go.

American company Omega Aerial Refueling Services operates two 707-320's. All the others are military aircraft and private 707's but the Omega jets come under the 'commercial' category on Wikipedia.

oldannyboy wrote:

Ok, saying that in 2017 B707s are still flying regularly is a bit of a stretch really...
back to topic: by the mid-80s those few 720s left flying were really old gas guzzlers and these were replaced with newer types at the end of their lives' cycles, and the were subsequently broken up. They were also carrying fewer pax than a 707(while burning give or take the same) so that may have had something to do with the fact that 707s were used longer. The speed/performance advantage of the 720 was pretty much irrelevant already by the early 1970s.

Indeed, the Boeing 720, and its cohorts the Convair 880 and 990, were conceived as medium-range companions to the larger 707s and DC8s during the late 50s. In service dates for these types were circa 1960-1962, two years before any 727s (the -100s) were in service, and a full 5-7 years before the 727-200s. The latter aircraft really was a 'death warrant' for the 720/880/990 since they offered more capacity and better economics on semi-transcons and the Northeast - Florida-Texas routes, which were important for EA, UA and BN. TW would have retired the 880 in the early 70s, but finances prevented them from loading up with more 727-231 at the time, and they soldiered on until June 1974. DL was loading up on 727-200s after the Northeast merger in 1972, meaning the end of the 880 by late 1973.

What's astounding is that this was happening prior to the first of the 1970s oil crises which hit starting late 1973. EA and UA had in fact retired the 720s in 1971 and in 1972, respectively. BN followed in the same time frame. All three had straight-pipe (non-fan) ships which apparently were dinosaurs after 10 years of service.

Western continued 720B ops well into the 1970s, but the fan engines were their saving grace. The 1979 oil crisis put an end to that, so by 1980, there was no trace of these fascinating four-engine birds in North American skies. AA flew a number of 720Bs during the 60s but I am not sure how long into the 70s they lasted (for scheduling purposes they were considered 707s).

They were all bought up for parts for the KC-135 fleet.

KLDC10 and CF-CPI are right on point. The 727 rendered the 720 obsolete. The 720 was basically a "domestic" version of the 707, tailored for short and medium haul routes. It had the wing of the 707-100, a lower fuel capacity, and also lacked the third air conditioning compressor that was on engine pylon 1. Boeing has made several models of existing airframes that have been a stop-gap between one model to the next, or simply a version of one model to fill the needs of customers that do not want to add another fleet type. WN and FR have been a huge driver to the continued existence of the 737, now 50 years old in design. It's no secret that the continued development of Boeing's cash cow was a detriment to the 757 program. And I mean that in respect to economics, not performance. The 737-800 was less expensive to procure and operate than the 757, as is the -900, providing a higher RPM and RASM between aircraft that have similar passenger capacities over domestic or international ops less than 2500nm.

The 720 was a great airplane for it's time. It's a 1960 design. They would be over 50 years old now. That's like asking why you don't see Model T's driving down the freeway.

For at least one airline the 720 turned out to be the wrong aircraft. Aer Lingus bought 3 of them for TAT operations from DUB to JFK and BOS via SHN. They were EI-ALA, LB and LC. The range of the 720 was barely adequate for the task. When headwinds were high, these aircraft frequently called in at Gander and other places for fuel. AFAIK there was a couple of fuel emergency landings with them also. A question someone might be able to answer: EI-ALB left the fleet years before the other 2 due to what I understand was a structural problem. Anyone know anything about this? Cheeers.

People have answered the question above, however for me the 720 was the first aircraft I ever flew on: 1979 Monarch Boeing 720B

Me,too! Olympic airways SX-DBK in October 1975. I was 15 years old. The 720B accelerated rapidly,had a relatively short take off run, and gained altitude in a spectacular way. What a performance! What an airplane!

IMO, two of the most beautiful jetliners of that era were the Northwest Orient 720B and the Delta Convair 880.

oldannyboy wrote:

Some of the very last 720s were operated by Danish airline Conair, which I remember were still regularly plying the "sun routes" in 1986-87. But boy, they were considered really ancient by then...

The 720Bs were phased out in 1987, when they suffered from 2 incidents where the nose-wheel assembly collapsed during landing (in Salzburg and Ciampino). At that time, Conair was already deep in negotiations to take over 3 x A300B2s from Scanair, which they did the same year.

I've flown the cockpit on those 720Bs many a times, a truly remarkable aircraft for its time - able to lift a full load of passengers off a short Greek runway during the hottest of summer days, and bring the lot back to Copenhagen at FL420 doing M0.88., or even M.90 if the skipper was in a hurry.

callumconroydub wrote:

OK, as seen as you asked, why would they be flying? And yes there are some 707's flying around, aren't there?

Hardly. By far most 707's ever produced have long been retired. And since there have been far more 707's than 720's ever produced it's no wonder the 720's aren't anymore. A very low percentage of all 707's ever produced still flying is still something, the same low percentage of all 720's ever produced is nothing. Add to that that the 720 wasn't exactly the most fuel-efficient aircraft and it's no wonder every single user wanted to get rid of them. A modern 737, same size as the 720 back then, can carry the same load at about 20 percent of the fuel burn of a 720. That's a significant difference. If an aircraft is too fuel-inefficient it's cheaper to replace it than to keep it.

I believe the Air Force gobbled up about every 707 available as spare parts for the KC 135 tanker fleet. While having a smaller tube, many parts transferred over. They were all parked at DMA and are still offering up their kidneys and lungs to this very day.

Everyone knows the 739 is the modern day twin engine 720... right ?

EIANV wrote:

EI-ALB left the fleet years before the other 2 due to what I understand was a structural problem. Anyone know anything about this? Cheeers.

According to another site (use Google) she flew up to 1976 with Pac Northern, Alaska, Pan Am, Western, and Aero America....

I flew the 720B at WAL and Pan Am. A real hot rod for its time and will still holds own with the 757 just as long as you have enough fuel. On a side note there were two different air-conditioning systems available, one freon and the other air cycle and the air cycle did not work well on he ground. Hot days in HNL or the western pacific could be brutal. Fortuneltly the 720's did not find their way out here very often.

BoeingGuy wrote:

That's like asking why you don't see Model T's driving down the freeway.

PatrickZ80 wrote:

And since there have been far more 707's than 720's ever produced it's no wonder the 720's aren't anymore. A very low percentage of all 707's ever produced still flying is still something, the same low percentage of all 720's ever produced is nothing.

So, refining BoeingGuy's car analogy based on the number produced, it might be more like asking why you never see any 1960s Studebaker Larks on the road. After all, there are still some 1960s Ford Mustangs on the road. The reason is there were never that many of the former built in the first place. And most of the old Mustangs you see are being driven by collectors/car enthusiasts, not as someone's regular daily driver, sort of like how John Travolta's 707 is one of the very few still flying (or is it still flying, actually?) as opposed to flying commercially in any capacity.

CF-CPI wrote:

Western continued 720B ops well into the 1970s, but the fan engines were their saving grace. The 1979 oil crisis put an end to that, so by 1980, there was no trace of these fascinating four-engine birds in North American skies. AA flew a number of 720Bs during the 60s but I am not sure how long into the 70s they lasted (for scheduling purposes they were considered 707s).

American took delivery of a total of 25 720s, 15 of which were built as fanjet powered 720Bs; the other (first) 10 were retrofitted with turbofan engines within 2-3 years after delivery. According to "Boeing 720" by Jon Proctor (a 'must have' for 720 enthusiasts!) AA's 720Bs began leaving their fleet in late 1970; the last departed on June 1, 1976. A total of 13 went to MEA who paid for these in part by returning Convair 990s they had acquired from AA only a few years earlier! (AA never put the returned 990s back into service)

spartanmjf wrote:

EIANV wrote:

EI-ALB left the fleet years before the other 2 due to what I understand was a structural problem. Anyone know anything about this? Cheeers.

According to another site (use Google) she flew up to 1976 with Pac Northern, Alaska, Pan Am, Western, and Aero America....

Indeed, I knew that she went on to other airlines and had a long career. I often wondered about a rumour that I had heard that the Fuselage was twisted slightly during
a pilot training flight and since that 'event' she was difficult to trim, was subject to occasional autopilot trips and used more fuel than her sisters. Aer Lingus may have been unwilling
or unable to fix the aircraft and so it was sold.It may be just a rumour. In any case the 707-320 becaome the backbone of Aer Lingus' TAT fleet until the arrival of the 747.

callumconroydub wrote:

I never knew the answer to this: why were the 720's retired? Could they not be still in use like the few 707's? What was wrong with them?

They were expensive to operate and most routes they flew could be done with 727's, would be my guess. I remember seeing UAL's parked, with engines removed at Stapleton many years ago. In the end, it boils down to economics.

The 720 had a lighter structure than the 707 and that did not endear it to longevity. The 707 had a lighter structure than the DC-8. The -8's outlived their lighter competitors. The 720B's truly were hot-rods and their take-off performance was stunning even when compared to an 880. I made many trips on both types and the 720B was my preference hands-down.

Towards the end of their service with NW they were converted to an all coach configuration with 3-2 seating and known as 720B "Specials".
The Advanced 727-200 series saw them off in a big way.

I've always found the 720 a fascinating plane. Imagine an aircraft with the same seating capacity as a 737-800, but with 4 screaming, smoking, thundering engines, a 3-man cockpit and a large, strongly swept wing. Add to that the atypical name for a Boeing. I think it's very cool. Compared to the innocuous 737, it was a beast, a thoroughbred.

But of course, the reasons that made it cool from an aviation enthusiast's point of view made it obsolete rather quickly. The 727 could do almost everything a 720 could, but with 3 engines, with far less fuel and noise, and it had much better short-field capabilities so it was more versatile.
(I'm not saying the 727 is not cool, it's one of my favourites in fact).

A shame was that the 720 was partly responsible for the demise of Convair's jet airliner programme: a 720B was just as fast as a CV880 or CV990 but was cheaper to operate, offered more seats and had cockpit commonality with the 707. Boeing priced the 720 quite agressively and Convair had no chance.

Later, the USAF bought a lot of 707s and 720s for spares to keep the large fleet of KC135s flying. That's also a reason why the 707/720 disappeared from the skies quicker than their rival, the DC8. Many people say that this was due to the better build quality of the Douglas, but in fact the USAF was an important factor too.

The -8 also had the advantage of a fuselage that could be stretched and the CFM mod kept them competitive on fuel costs.

GF

[threeid][/threeid]

GalaxyFlyer wrote:

The -8 also had the advantage of a fuselage that could be stretched and the CFM mod kept them competitive on fuel costs.

GF

That's absolutely true. Boeing tried a 707-700 with CFM56s too, but in the end it was regarded as a threat to the then-new 757 so the project was abandoned. However, the experience was useful for re-engining the KC-135(R) with CFMs later. And indeed, the DC8 could be stretched much easier than the 707, partly due to the taller landing gear. I think the stretched DC8 versions accounted for appr. 50% of total DC8 sales. Had the stretched DC8s not existed, the entire DC8 project would have been a failure: one could say that the stretching possibilities that were designed into the DC8 saved the entire project. The DC8-60 series was more or less the link between the 707-300B and the 747.

global1 wrote:

IMO, two of the most beautiful jetliners of that era were the Northwest Orient 720B and the Delta Convair 880.

If you write in Search: "Boeing 720-051B" you will see a lot of them. The Taiwanese 720-051B Is now on display in a hangar. They know what a treasure they have. On the contrary, when Honeywell retired their own 720-051B, they put it up for sale for $500.000 instead of donating it to a museum. And when they understood there was to be no interest,as museums depend on donations and volunteer work,they smeared it with signatures and "miss you" comments and had it scrapped. That's how much they loved it...thank you honey,well done!

EIANV wrote:

For at least one airline the 720 turned out to be the wrong aircraft. Aer Lingus bought 3 of them for TAT operations from DUB to JFK and BOS via SHN. They were EI-ALA, LB and LC. The range of the 720 was barely adequate for the task. When headwinds were high, these aircraft frequently called in at Gander and other places for fuel. AFAIK there was a couple of fuel emergency landings with them also. A question someone might be able to answer: EI-ALB left the fleet years before the other 2 due to what I understand was a structural problem. Anyone know anything about this? Cheeers.

I always think EI (or to be more accurate, IN, since that was the code Aerlinte used) would have been better off with the -320 or the -100B (like the ones QF used), but they went with very conservative estimates of loads. The transatlantic service was launched in 1958 and the loads on that (a Connie with about 60-70 seats) were only about meagre - 40-50% or so. With that in mind, their estimates for loads on a jet service had to be very conservative. They looked at DC8s, Convairs (which didn't have a great range) and 707s, but eventually settled on the 720. The 720s served EI will, but as EIANV has pointed out, there were quite a few diversions; indeed, when they got up to about 70%, they were in the danger zone for diversions. These were always westbound; strong tailwinds always helped and the 720 could easily do IDW-SNN in less than 5h.

(I never heard about a structural problem involving EI-ALB specifically, but I'll try and find out.)

Eventually, the level of landings did become embarrassing, because traffic was climbing; the first 707 joined the fleet in 1964 and from then on, the 720s were leased to a variety of airlines, including Braniff, EL AL, TEA and others. They did return for short periods, but never did the prime t/a runs again.

Getting back to the thread subject, the 720 was a low capacity aircraft (in the two class IN layout, they seated 115) and the 727s could carry more with fewer engines. United retired theirs by 1969 and American, Braniff, Eastern and TWA also retired theirs (not sure if they were all gone by 1970, but most anyway). The 720 can be compared to the original mobile phone "bricks" or Commodore 64 computers - a good first effort, but superseded and rendered obsolete by what followed.

berari wrote:

callumconroydub wrote:

I never knew the answer to this: why were the 720's retired? Could they not be still in use like the few 707's? What was wrong with them?

How many 707s do you know of that are in service? Airlines and routes?

Are 707s still flying for that airline in Iran? I know they kept them just about longer than any other airline.

global2 wrote:

berari wrote:

callumconroydub wrote:

I never knew the answer to this: why were the 720's retired? Could they not be still in use like the few 707's? What was wrong with them?

How many 707s do you know of that are in service? Airlines and routes?

Are 707s still flying for that airline in Iran? I know they kept them just about longer than any other airline.

That's because the Iranians had a hard time buying just about anything in the past couple of decades.


As for the OP's question:
Like all old planes, the 720s were replaced by more efficient designs.
Note: The same answer applies to most of your threads

WAL, the largest operator by far of the 720B bumped the center tank fuel capacity by a few thousand pounds and increased the GW by something in the order of 6,000# which put the airplane around 236,000 as I recall? these airplanes were equipped with dual Bendix Doppler and a Loran A unit for HNL operations. Don't recall if CAL did something similar to their small fleet of 720B's as well?

KLDC10 wrote:

The last Boeing 720 was retired in 2010. See: https://www.wingsmagazine.com/news/worl ... tires-4553

Only 154 Boeing 720s were ever built. Better and more economical aircraft came along (e.g. the Boeing 727), superseding the Boeing 720 and rendering it obsolete. That's just the way things go.

Here is a link to a youtube movie of the last fligth of the 720. Date of last flight is may 9, 2012 according to this movie.
https://www.youtube.com/watch?v=qp3w8rMMA1A